This study compared the effects of clinically prescribed doses of cilazapril, nifedipine, and atenolol on maximal exercise performance in physically active subjects. In a double-blind crossover trial, 10 healthy male volunteers performed progressive aerobic exercise to exhaustion for determination of maximal oxygen consumption (VO2 max), after single dose ingestion of cilazapril, nifedipine, atenolol, and placebo. Measurements were made at exhaustion and at a single submaximal workload (250 W). Exercise time to exhaustion and peak workload were decreased by all agents (p less than 0.05 vs. placebo), but VO2 max was decreased by atenolol only (p less than 0.05 vs. placebo). Although both atenolol and cilazapril decreased the maximum systolic blood pressure, the peak heart rate was decreased only by atenolol (p less than 0.001 vs. placebo). Whereas submaximal oxygen consumption, minute ventilation, and blood lactate concentrations were not different between groups, ratings of perceived exertion were increased during submaximal exercise by atenolol and cilazapril (p less than 0.05 vs. placebo). Cilazapril, nifedipine, and atenolol all impaired exercise performance and increased ratings of perceived exertion during submaximal exercise without altering rates of oxygen consumption or blood lactate accumulation. Maximal exercise performance was impaired to a greater extent by atenolol than by nifedipine or cilazapril. This study suggests that either angiotensin-converting enzyme inhibitors or calcium-channel antagonists might be preferable for the management of hypertension in athletic patients as they have a lesser effect on exercise performance, at least in healthy individuals.