user426: I play the French defence with both colours (white and black) and generally play any of the orthodox main line openings (there are many eg Advance, Exchange, Classical,Tarrasch etc giving rise to many variations as openings and defence variation eg early ...Qb6 Wade var.). 
There are some gambit openings from the White side and as white I often play the Milner-Barry Gambit and have started to reacquaint myself with the Alapin-Diemer (I sometimes face the MBG as black). So far though I have not encountered a gambit line for the black side in the French and so wonder if there are any such playable black French gambit opening lines?
If anyone knows one or more I'd be interested to hear.
I look forward to replies and comments, but meanwhile I will keep searching myself to find such a gambit for black in the French defence opening.....

user1712: There is a pawn sacrifice in the shown c5 line of the Tarrasch variation. Normally, it's temporary and black gets the c5 pawn back, but white can try to hang to it with moves like Nb3, Be3, ... although it's unlikely the best way to play the opening.
[FEN ""]
1. e4 e6 2. d4 d5 3. Nd2 c5 4. exd5 exd5 5. Bb5+ Nc6 6. Qe2+ Be7 7. dxc5


user1813: I am a 2210 FIDE-rated player and I have played the French defence in tournaments as a primary defence to 1. e4 since I was a child. Although you may find gambit lines on the Black side in some variations (as many good answers here have shown), you will not be able to play such gambits unless White is cooperative and willing to play against them. The fact is just that there exist rather few reputable gambits for Black in the orthodox openings - the Marshall gambit in the Ruy Lupez being one of the exceptions. If you are a tactical player and like to sacrifice material, I recommend that instead of looking for questionable gambits, you aim for dynamic positions where tactical manuevers and sacrifices are likely to be an option in the middle game. The Flexible French by Moskalenko is a good reference.

user1485: There is also the gambit from the game Capablanca-Alekhine (St Petersburg, 1914), but it's not very good.
[fen ""]

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 h6 (4...Be7;4...Bb4)5. Bxf6 Qxf6 6. exd5 Bb4 7. Bb5+

The check is annoying. If black could castle without disturbance, this gambit would perhaps be playable.
I have thought about using the same idea one move later
[fen ""]

1. e4 e6 2. d4 d5 3. Nc3 a6 4. Nf3 Nf6 5. Bg5 h6!?

but I'm not sure about it, and besides white has too many options before reaching this position.

user307: Here is one line:
[fen ""]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7 5. e5 Nfd7 6. h4 c5 7. Bxe7 Qxe7 8. Nb5 O-O 9. Nc7 Nc6 10. Nxa8 cxd4

Black has castled, and is pretty well developed, while the white king is still in the center, and white does not have one normally developed piece. You probably won't find many games with professionals playing the line, but here is one interesting draw with Nigel Short handling the black pieces:
[fen ""]
[Event "Bunratty Masters"]
[Site "Bunratty"]
[Date "2011.02.26"]
[Round "2"]
[White "Hunt, Adam"]
[Black "Short, Nigel D"]
[Result "1/2-1/2"]
[WhiteElo "2436"]
[BlackElo "2658"]
[ECO "C14"]
[EventDate "2011.02.25"]
[PlyCount "142"]
[SourceDate "2011.05.03"]

1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.Bg5 Be7 5.e5 Nfd7 6.h4 c5 7.Bxe7 Qxe7 8.Nb5 
O-O 9.Nc7 Nc6 10.Nxa8 cxd4 11.Nf3 Qb4+ 12.Qd2 Qxb2 13.Rd1 Nc5 14.Bd3 Bd7 
15.Nc7 Rc8 16.Nxd5 exd5 17.O-O a6 18.Qf4 h6 19.Rb1 Qc3 20.Rfd1 b5 21.Kh2 
Re8 22.g4 Ne4 23.Bxe4 dxe4 24.Qxe4 Qc5 25.Re1 Be6 26.Rbd1 Bd5 27.Qd3 Bxf3 
28.Qxf3 Nxe5 29.Qe4 Re6 30.Qa8+ Kh7 31.Qe4+ g6 32.Kg2 Qc3 33.Qf4 Qc6+ 34.
Qe4 Nd3 35.cxd3 Rxe4 36.dxe4 Qe6 37.Rxd4 Qxg4+ 38.Kf1 Qxh4 39.Re3 Kg7 40.
Rd7 Qh1+ 41.Ke2 Qc1 42.e5 Qc2+ 43.Kf1 Qc4+ 44.Ke1 Qe6 45.Rd6 Qxa2 46.e6 
Qb1+ 47.Ke2 Qc2+ 48.Kf1 Qc4+ 49.Kg2 fxe6 50.Rexe6 Qg4+ 51.Kf1 h5 52.Rxa6 
h4 53.Re7+ Kh6 54.Re3 h3 55.Raa3 Qg2+ 56.Ke2 h2 57.Rh3+ Kg7 58.Ra7+ Kg8 
59.Rah7 Qe4+ 60.Kd2 Qd4+ 61.Ke2 g5 62.R7h5 Qe4+ 63.Kd2 Qf4+ 64.Ke2 b4 65.
Rh8+ Kf7 66.Rf3 Kg7 67.Rfh3 Qe4+ 68.Kd2 Qd4+ 69.Kc2 Qxf2+ 70.Kb3 Qd4 71.
R3h7+ Kg6 1/2-1/2

Black might be better of by playing 9...cxd4 instead of 9...Nc6, For example: Bronstein - Stahlberg:
[fen ""]
[Event "Budapest Candidates"]
[Site "Budapest, HUN"]
[Date "1950.04.24"]
[EventDate "1950.??.??"]
[Round "8"]
[Result "0-1"]
[White "David Bronstein"]
[Black "Gideon Stahlberg"]
[ECO "C13"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "92"]

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7 5. e5 Nfd7 6. h4 c5
7. Bxe7 Qxe7 8. Nb5 O-O 9. Nc7 cxd4 10. Nxa8 f6 11. Qxd4 Nc6
12. Qd2 fxe5 13. O-O-O Nf6 14. f3 Qd6 15. Ne2 Bd7 16. Nc3 Rxa8
17. Ne4 Qe7 18. Nxf6+ Qxf6 19. Bb5 Nb8 20. Qb4 Bxb5 21. Qxb5
Qf7 22. c4 Nc6 23. cxd5 Nd4 24. Qd3 exd5 25. Rhf1 Qf4+ 26. Kb1
Rd8 27. g3 Qxg3 28. f4 Qxd3+ 29. Rxd3 Nc6 30. fxe5 Nxe5
31. Rd4 Nc6 32. Rdf4 Ne5 33. Rf5 Nc4 34. R1f2 d4 35. b3 d3
36. bxc4 d2 37. Rxd2 Rxd2 38. Rb5 b6 39. Re5 Rd4 40. c5 Rxh4
41. Re8+ Kf7 42. Ra8 Rb4+ 43. Ka1 bxc5 44. Rxa7+ Kf6 45. Ra5
g5 46. Rxc5 g4 0-1


user291: There's the Poisoned Pawn variation of the Winawer:
[fen ""]

1. e4 e6
2. d4 d5
3. Nc3 Bb4
4. e5 c5
5. a3 Bxc3+
6. bxc3 Ne7
7. Qg4 Qc7
8. Qxg7 Rg8
9. Qxh7 cxd4

In general, though, it's hard to find a good pawn for Black to give away in the French.

426: <p>I play the French defence with both colours (white and black) and generally play any of the orthodox main line openings (there are many eg Advance, Exchange, Classical,Tarrasch etc giving rise to many variations as openings and defence variation eg early ...Qb6 Wade var.). </p>

<p>There are some gambit openings from the White side and as white I often play the Milner-Barry Gambit and have started to reacquaint myself with the Alapin-Diemer (I sometimes face the MBG as black). So far though I have not encountered a gambit line for the black side in the French and so wonder if there are any such playable black French gambit opening lines?</p>

<p>If anyone knows one or more I'd be interested to hear.
I look forward to replies and comments, but meanwhile I will keep searching myself to find such a gambit for black in the French defence opening.....</p>
 1712: <p>There is a pawn sacrifice in the shown c5 line of the Tarrasch variation. Normally, it's temporary and black gets the c5 pawn back, but white can try to hang to it with moves like Nb3, Be3, ... although it's unlikely the best way to play the opening.</p>

<pre><code>[FEN ""]
1. e4 e6 2. d4 d5 3. Nd2 c5 4. exd5 exd5 5. Bb5+ Nc6 6. Qe2+ Be7 7. dxc5
</code></pre>
 1813: <p>I am a 2210 FIDE-rated player and I have played the French defence in tournaments as a primary defence to 1. e4 since I was a child. Although you may find gambit lines on the Black side in some variations (as many good answers here have shown), you will not be able to play such gambits unless White is cooperative and willing to play against them. The fact is just that there exist rather few reputable gambits for Black in the orthodox openings - the Marshall gambit in the Ruy Lupez being one of the exceptions. If you are a tactical player and like to sacrifice material, I recommend that instead of looking for questionable gambits, you aim for dynamic positions where tactical manuevers and sacrifices are likely to be an option in the middle game. The Flexible French by Moskalenko is a good reference.</p>
 1485: <p>There is also the gambit from the game Capablanca-Alekhine (St Petersburg, 1914), but it's not very good.</p>

<pre><code>[fen ""]

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 h6 (4...Be7;4...Bb4)5. Bxf6 Qxf6 6. exd5 Bb4 7. Bb5+
</code></pre>

<p>The check is annoying. If black could castle without disturbance, this gambit would perhaps be playable.</p>

<p>I have thought about using the same idea one move later</p>

<pre><code>[fen ""]

1. e4 e6 2. d4 d5 3. Nc3 a6 4. Nf3 Nf6 5. Bg5 h6!?
</code></pre>

<p>but I'm not sure about it, and besides white has too many options before reaching this position.</p>
 307: <p>Here is one line:</p>

<pre><code>[fen ""]
1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7 5. e5 Nfd7 6. h4 c5 7. Bxe7 Qxe7 8. Nb5 O-O 9. Nc7 Nc6 10. Nxa8 cxd4
</code></pre>

<p>Black has castled, and is pretty well developed, while the white king is still in the center, and white does not have one normally developed piece. You probably won't find many games with professionals playing the line, but here is one interesting draw with Nigel Short handling the black pieces:</p>

<pre><code>[fen ""]
[Event "Bunratty Masters"]
[Site "Bunratty"]
[Date "2011.02.26"]
[Round "2"]
[White "Hunt, Adam"]
[Black "Short, Nigel D"]
[Result "1/2-1/2"]
[WhiteElo "2436"]
[BlackElo "2658"]
[ECO "C14"]
[EventDate "2011.02.25"]
[PlyCount "142"]
[SourceDate "2011.05.03"]

1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.Bg5 Be7 5.e5 Nfd7 6.h4 c5 7.Bxe7 Qxe7 8.Nb5 
O-O 9.Nc7 Nc6 10.Nxa8 cxd4 11.Nf3 Qb4+ 12.Qd2 Qxb2 13.Rd1 Nc5 14.Bd3 Bd7 
15.Nc7 Rc8 16.Nxd5 exd5 17.O-O a6 18.Qf4 h6 19.Rb1 Qc3 20.Rfd1 b5 21.Kh2 
Re8 22.g4 Ne4 23.Bxe4 dxe4 24.Qxe4 Qc5 25.Re1 Be6 26.Rbd1 Bd5 27.Qd3 Bxf3 
28.Qxf3 Nxe5 29.Qe4 Re6 30.Qa8+ Kh7 31.Qe4+ g6 32.Kg2 Qc3 33.Qf4 Qc6+ 34.
Qe4 Nd3 35.cxd3 Rxe4 36.dxe4 Qe6 37.Rxd4 Qxg4+ 38.Kf1 Qxh4 39.Re3 Kg7 40.
Rd7 Qh1+ 41.Ke2 Qc1 42.e5 Qc2+ 43.Kf1 Qc4+ 44.Ke1 Qe6 45.Rd6 Qxa2 46.e6 
Qb1+ 47.Ke2 Qc2+ 48.Kf1 Qc4+ 49.Kg2 fxe6 50.Rexe6 Qg4+ 51.Kf1 h5 52.Rxa6 
h4 53.Re7+ Kh6 54.Re3 h3 55.Raa3 Qg2+ 56.Ke2 h2 57.Rh3+ Kg7 58.Ra7+ Kg8 
59.Rah7 Qe4+ 60.Kd2 Qd4+ 61.Ke2 g5 62.R7h5 Qe4+ 63.Kd2 Qf4+ 64.Ke2 b4 65.
Rh8+ Kf7 66.Rf3 Kg7 67.Rfh3 Qe4+ 68.Kd2 Qd4+ 69.Kc2 Qxf2+ 70.Kb3 Qd4 71.
R3h7+ Kg6 1/2-1/2
</code></pre>

<p>Black might be better of by playing <code>9...cxd4</code> instead of <code>9...Nc6</code>, For example: Bronstein - Stahlberg:</p>

<pre><code>[fen ""]
[Event "Budapest Candidates"]
[Site "Budapest, HUN"]
[Date "1950.04.24"]
[EventDate "1950.??.??"]
[Round "8"]
[Result "0-1"]
[White "David Bronstein"]
[Black "Gideon Stahlberg"]
[ECO "C13"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "92"]

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7 5. e5 Nfd7 6. h4 c5
7. Bxe7 Qxe7 8. Nb5 O-O 9. Nc7 cxd4 10. Nxa8 f6 11. Qxd4 Nc6
12. Qd2 fxe5 13. O-O-O Nf6 14. f3 Qd6 15. Ne2 Bd7 16. Nc3 Rxa8
17. Ne4 Qe7 18. Nxf6+ Qxf6 19. Bb5 Nb8 20. Qb4 Bxb5 21. Qxb5
Qf7 22. c4 Nc6 23. cxd5 Nd4 24. Qd3 exd5 25. Rhf1 Qf4+ 26. Kb1
Rd8 27. g3 Qxg3 28. f4 Qxd3+ 29. Rxd3 Nc6 30. fxe5 Nxe5
31. Rd4 Nc6 32. Rdf4 Ne5 33. Rf5 Nc4 34. R1f2 d4 35. b3 d3
36. bxc4 d2 37. Rxd2 Rxd2 38. Rb5 b6 39. Re5 Rd4 40. c5 Rxh4
41. Re8+ Kf7 42. Ra8 Rb4+ 43. Ka1 bxc5 44. Rxa7+ Kf6 45. Ra5
g5 46. Rxc5 g4 0-1
</code></pre>
 291: <p>There's the Poisoned Pawn variation of the Winawer:</p>

<pre><code>[fen ""]

1. e4 e6
2. d4 d5
3. Nc3 Bb4
4. e5 c5
5. a3 Bxc3+
6. bxc3 Ne7
7. Qg4 Qc7
8. Qxg7 Rg8
9. Qxh7 cxd4
</code></pre>

<p>In general, though, it's hard to find a good pawn for Black to give away in the French.</p>
