The purpose of this study was to assess whether maximal oxygen uptake (V.O(2 max)) could be predicted from submaximal ratings of perceived exertion (RPE) elicited during the multistage fitness test (MFT). Eleven female volunteers completed three maximal exercise tests in random order; the MFT, a simulated MFT on a motorized treadmill and a graded exercise test to volitional exhaustion (GXT), also on a motorized treadmill. RPE values were recorded at the end of each 1 min stage in all three tests. Oxygen consumption (VO(2)) was recorded continuously during the treadmill tests. Measured V.O(2 max) values from the GXT and simulated MFT were not significantly different (48.2 and 47.5 ml/kg/min, respectively), but they were significantly higher than V.O(2 max) values predicted by the MFT (41.2 ml/kg/min, p<0.05). Regression of submaximal RPE values (7-17) elicited from the MFT and VO(2) values predicted by the MFT were extrapolated to RPE 20 to predict V.O(2 max). The RPE-predicted V.O(2 max) from the MFT (47.5 ml/kg/min) was similar to measured V.O(2 max). The findings suggest that submaximal RPE values can be used to provide acceptable estimates of V.O(2 max) which are more accurate than the published table values for the MFT. Furthermore, the use of RPE measures in conjunction with the MFT enhances the accuracy of V.O(2 max) prediction by the MFT.