Purpose: This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain during moderate-intensity cycling exercise among females. Methods: Low-caffeine- consuming college-aged females (N = 11) ingested one of two doses of caffeine (5 or 10 mg·kg-1 body weight) or a placebo and 1 h later completed 30 min of cycling on an ergometer at approximately 60% V̇O 2peak. The conditions were completed in a counterbalanced order. Perceptions of leg muscle pain as well as power output, heart rate, systolic blood pressure, and oxygen consumption (V̇O2) were recorded during exercise. Results: Caffeine had a significant effect on leg muscle pain ratings [F (2,20) = 10.63, P = 0.001, Latin small letter Eng2 = 0.52]. The mean pain intensity scores during exercise after ingesting 10 mg·kg-1 body weight caffeine, 5 mg·kg-1 body weight caffeine, and placebo were 1.6 ± 1.1, 1.3 ± 0.7, and 2.4 ± 1.1, respectively. Conclusion: The results support that caffeine ingestion has a large effect on reducing leg muscle pain during exercise among females, but this effect does not appear to be dose-dependent between 5 and 10 mg·kg-1 body weight caffeine. Copyright © 2006 by the American College of Sports Medicine.