The purpose was to assess the validity of predicting peak oxygen uptake from Ratings of Perceived Exertion (RPE)≤15, during a graded exercise test (GXT), in obese women. Forty-three obese women performed GXT to volitional exhaustion. During GXT, oxygen uptake and RPE were measured. Individual linear regressions between and RPE≤15 were extrapolated to RPE 20 in order to predict . Actual and predicted were not significantly different (13.9±3.0 vs 14.2±3.3 ml kg−1 min−1, respectively; p=.26). The Pearson product moment correlation between actual and predicted was high (r=0.82). The 95% limits of agreement analysis on these values (bias±1.96SD) was −0.3±3.7 ml kg−1 min−1. Results suggested that RPE≤15 elicited during a sub-maximal GXT provides accurate prediction. Therefore, it is not necessary to perform GXT to voluntary exhaustion to determine in obese women.