This study assessed the validity and reliability of the Cantonese-translated version of the Borg 6-20 Rating of Perceived Exertion (RPE) scale during continuous incremental cycle ergometry by Hong Kong adults. A total of 54 participants (25 males and 29 females), ages 22.2 +/- 4.7 yr., volunteered to participate. They performed two trials of identical continuous incremental cycling exercise 1 wk. apart for the reliability test. The objective measures of exercise intensity (heart rate, power output, and oxygen consumption) and the subjective measure of effort (RPE) were obtained during the incremental exercise. Significant (p < .01) Pearson correlations were found when RPE values were correlated with heart rate (rs > or = .73), power output (rs > or = .69), and oxygen consumption (rs > or = .68). The overall test-retest intraclass correlation (R = .92) indicated that the scale was reliable. In conclusion, this Cantonese scale for rating of perceived exertion appears to be a valid and reliable psychophysiological tool to measure perceptions of exertion during controlled cycle ergometer exercise by Hong Kong adults.