The purpose of the present study was to increase the accuracy of prediction of VO2max from the Canadian Aerobic Fitness Test (CAFT) by modifying the protocol and developing a new equation. Males and females between the ages of 15 and 69 years (n = 129) were tested on four occasions. Each subject performed four submaximal step tests (modified CAFT protocol) and a maximal treadmill test. The modification of the protocol consisted of allowing each subject to complete the number of stages needed to reach a target heart rate of 85% of age-predicted maximum. This required adding a new Stage 8 for men and Stages 7 and 8 for women. The prediction equation resulting from regression analysis was, VO2max (ml.kg-1 x min-1) = 32.0 + 16.0 VO2 - 0.24 Age - 0.17 Wt (R2 - 0.77; delta 2 - 26.6), where VO2 = oxygen cost of stepping at the final level (L.min-1), Age = age (yrs), and Wt = body mass (kg).