The effects of caffeine on anaerobic exercise in young boys was investigated. Twenty-four healthy 8–10 year old boys participated in a randomized doubleblind, double-crossover, counter-balanced study. Each subject received the caffeinated drink (CAF—5 mg · kg−1) or placebo (PL) twice each on four separate visits. Sixty minutes following ingestion of either CAF or PL boys performed a static hand-grip test and then a Wingate test. Reliability was moderately high for the Wingate test (R = .70–0.95). Hand-grip reliability was higher for CAF (R = .88) than PL (R = .52). Mean power (180 ± 36 vs 173 ± 28 W) was significantly higher (p < .05) in CAF versus PL, respectively. There were no differences in peak power or static hand-grip maximal voluntary contraction with CAF. Further, peak HR (190 ± 10 vs 185 ± 10 beats · min−1) was significantly higher in CAF versus PL, respectively. Thus, in this study a moderately high dose of CAF significantly increased the average power during a Wingate test, yet it does not affect peak power or static hand-grip strength.