Several studies have reported that the insertion (I) allele of the angiotensin-converting enzyme (ACE) I/deletion (D) polymorphism is associated with enhanced responsiveness to endurance training and is more common in endurance athletes than in sedentary controls. We tested the latter hypothesis in a cohort of 192 male endurance athletes with maximal oxygen uptake >/=75 ml. kg(-1). min(-1) and 189 sedentary male controls. The ACE ID polymorphism in intron 16 was typed with the three-primer polymerase chain reaction method. Both the genotype (P = 0.214) and allele (P = 0.095) frequencies were similar in the athletes and the controls. Further analyses in the athletes revealed no excess of the I allele among the athletes within the highest quartile (> 80 ml. kg(-1). min(-1)) or decile (>83 ml. kg(-1). min(-1)) of maximal oxygen uptake. These data from the GENATHLETE cohort do not support the hypothesis that the ACE ID polymorphism is associated with a higher cardiorespiratory endurance performance level.