The objective of this study was to evaluate the utility of the Canadian Aerobic Fitness Test (CAFT), a field measure of cardiovascular fitness. After providing anthropometric measures, 31 subjects, ages 10 to 15, completed a maximal treadmill test and the CAFT, a 3-stage step test. Multiple regression analyses were conducted where maximal oxygen consumption from the treadmill test was estimated based on the oxygen cost of stepping, age and various combinations of body composition. For the total sample, the best model (R = 0.79, SEE = 6.7), obtained from the sum of 4 skinfolds, was the body composition estimate. This model was slightly more accurate for males (R = 0.83, SEE = 6.0) than for females (R = 0.77, SEE = 7.0). When the regression equation incorporated less time consuming indicators of body composition, the predictive power, albeit lower, was still satisfactory. It appears that the CAFT can be a useful option for measuring cardiovascular fitness for youth, with the decision dependent on the purpose of the test, the testing resources, the setting, and the motivation of the subjects.