The blood pressure (BP) response during a maximal ergometer bicycle test was studied in 190 apparently healthy subjects (95 men and 95 women) aged 21-70 years. The starting load was 50 W and was increased by 50 W every 4 min until exhaustion. Mean physical performance expressed as cumulative work was 2276 +/- 789 W in men and 1109 +/- 276 W in women (P less than 0.0001). The maximum heart rate was similar in men and women and declined significantly with age (r = -0.78, P less than 0.001 for men and r = -0.64, P less than 0.0001 for women). The mean maximal systolic blood pressure (MSBP) was 193 +/- 23 mmHg in men and 171 +/- 21 mmHg in women (P less than 0.0001). Men aged greater than or equal to 50 years had a MSBP of 201 +/- 22 mmHg, compared to 188 +/- 22 mmHg in those aged less than 50 years (P less than 0.01). Women aged greater than or equal to 60 years had a MSBP of 190 +/- 21 mmHg compared to 166 +/- 19 mmHg in their younger counterparts (P less than 0.001). The diastolic BP showed a similar modest increase at all ages and in both sexes. SBP is dependent on age and gender and this must be taken into consideration when assessing a normal response in individual patients.