The purpose of this investigation was to assess the effect of resistance exercise performed to volitional failure on ratings of perceived exertion (RPE) using power as an indication of fatigue. 12 male participants (M age = 21.9 yr., SD = 1.3) performed one set of back squats at three different intensities (50%, 70%, and 90% of one repetition maximum) for both a pre-determined number of repetitions (3) and to volitional failure. RPE was significantly different between sets at 50%, 70%, and 90% when performed to a pre-determined number of repetitions, but not during volitional failure. A decrease in power between the first and the last repetitions in the volitional failure sets suggests that fatigue may confound the relationship between RPE and intensity.