Forty-three pairs and 10 triplets of bicycle exercise tests were performed. Seven different workload incremental procedures were used. Triplets and nine pairs of tests were performed by healthy subjects (n = 19) and 34 pairs of tests by patients (n = 19) 3 and 15 months after coronary by-pass operation. From each test result a hypothetical maximal workload sustainable for 6 min (Wmax6') was calculated. The two and three Wmax6' values obtained for each pair and each triplet of tests, respectively, were compared. The ratios between the corresponding Wmax6' values were 1.00 +/- 0.01 (mean +/- SE) for healthy subjects and 0.96 +/- 0.03 for patients. It is concluded that working capacities determined by bicycle exercise tests with different workload incremental procedures can be compared via the Wmax6'.