user4020: I am losing a game. My only option is to check my opponent non stop. I have no chance to checkmate him. I am only hoping to force a draw. Is this proper chess etiquette?

user9082: Yes, this is good sportsmanship. In fact, the perpetual check is the most important defensive tactic in the Queen+pawn vs Queen endgame. 
I can add the following to the previous answers. Other variants of chess have a different opinion about this question. For example, in Chinese Chess, it is forbidden to make perpetual check. See, for example, this resource.
I hope that my contribution is not too far from the topic.

user2429: Yes, it is proper chess etiquette. You are not obliged to resign if you have an inferior position. If you can force a 3-move repetition draw by non-stop checks (called "perpetual checks") you definitely should. Players at the highest level have done this.
In fact, we even celebrate some games which have ended with perpetual check by the side with the weaker material. Consider the famous "Immortal Draw" game - 
Carl Hamppe vs Philipp Meitner 1872, 1/2-1/2 
  [Event "Vienna"]
  [Site "Vienna"]
  [Date "1872"]
  [Result "1/2-1/2"]
  [White "Carl Hamppe"]
  [Black "Philipp Meitner"]
  [FEN ""]

  1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2+ 4. Kxf2 Qh4+ 5. Ke3 Qf4+ 
  6. Kd3 d5 7. Kc3 Qxe4 8. Kb3 Na6 9. a3 Qxa4+ 10. Kxa4 Nc5+
  11. Kb4 a5+ 12. Kxc5 Ne7 13. Bb5+ Kd8 14. Bc6 b6+ 15. Kb5 Nxc6
  16. Kxc6 Bb7+ 17. Kb5 Ba6+ 18. Kc6 Bb7+ 1/2-1/2


user3445: What you are describing is Perpetual Check: http://en.wikipedia.org/wiki/Perpetual_check
It is covered in the rules of chess and the result of such a game is a draw. It is up to your opponent to try and avoid this situation if he thinks he can win. Conversely, if you might lose you should try to get into some kind of draw situation to avoid a loss.
Anecdote: A queen vs. queen, knight, and bishop did the same thing at the club quick tournament last night.

4020: <p>I am losing a game. My only option is to check my opponent non stop. I have no chance to checkmate him. I am only hoping to force a draw. Is this proper chess etiquette?</p>
 9082: <p>Yes, this is good sportsmanship. In fact, the perpetual check is the most important defensive tactic in the <a href="https://en.wikipedia.org/wiki/Queen_and_pawn_versus_queen_endgame" rel="nofollow">Queen+pawn vs Queen endgame</a>. </p>

<p>I can add the following to the previous answers. Other variants of chess have a different opinion about this question. For example, in Chinese Chess, it is forbidden to make perpetual check. See, for example, <a href="http://www.clubxiangqi.com/rules/d1to3.htm" rel="nofollow">this resource</a>.</p>

<p>I hope that my contribution is not too far from the topic.</p>
 2429: <p>Yes, it is proper chess etiquette. You are not obliged to resign if you have an inferior position. If you can force a 3-move repetition draw by non-stop checks (called "<strong>perpetual checks</strong>") you definitely should. Players at the highest level have done this.</p>

<p>In fact, we even celebrate some games which have ended with perpetual check by the side with the weaker material. Consider the famous "<strong>Immortal Draw</strong>" game - </p>

<p><a href="http://www.chessgames.com/perl/chessgame?gid=1250160">Carl Hamppe vs Philipp Meitner 1872, 1/2-1/2</a>  </p>

<pre><code>  [Event "Vienna"]
  [Site "Vienna"]
  [Date "1872"]
  [Result "1/2-1/2"]
  [White "Carl Hamppe"]
  [Black "Philipp Meitner"]
  [FEN ""]

  1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2+ 4. Kxf2 Qh4+ 5. Ke3 Qf4+ 
  6. Kd3 d5 7. Kc3 Qxe4 8. Kb3 Na6 9. a3 Qxa4+ 10. Kxa4 Nc5+
  11. Kb4 a5+ 12. Kxc5 Ne7 13. Bb5+ Kd8 14. Bc6 b6+ 15. Kb5 Nxc6
  16. Kxc6 Bb7+ 17. Kb5 Ba6+ 18. Kc6 Bb7+ 1/2-1/2
</code></pre>
 3445: <p>What you are describing is Perpetual Check: <a href="http://en.wikipedia.org/wiki/Perpetual_check">http://en.wikipedia.org/wiki/Perpetual_check</a></p>

<p>It is covered in the rules of chess and the result of such a game is a draw. It is up to your opponent to try and avoid this situation if he thinks he can win. Conversely, if you might lose you should try to get into some kind of draw situation to avoid a loss.</p>

<p>Anecdote: A queen vs. queen, knight, and bishop did the same thing at the club quick tournament last night.</p>
