The 2003–04 Heineken Cup was a best ever for Biarritz, as they made it to the semi-finals for the first time. They finished at the top of their pool and defeated the Llanelli Scarlets in the quarter-finals. They lost to fellow French club Toulouse 19–11 in the semi-finals. In 2004–05 Biarritz dropped only the one pool game against the London Wasps and finished at the top of their pool. They then defeated Munster in the quarter-finals, to repeat their success of the previous season by making the semi-finals. They however lost to Stade Français, 20–17 at Parc des Princes. More success followed in 2005, where they defeated the Stade Français club 37 points to 34 in the domestic final after a very rugged challenge.