Although studies have reported the positive effects of caffeine on aerobic performance, results of its ergogenic effects on anaerobic performance and intense and short-term exercise are equivocal. The aim of this study was to determine the effect of moderate and low doses of caffeine on maximal strength, muscular endurance and power in male body builders. For this purpose, 12 male body builders (mean age 26.83±5years, height 174±4.04 cm and body weight 77.41±3.8 kg) were selected voluntarily. Study design was crossover. Subjects were divided into four groups of control, low dose of caffeine (2.5 mg/kg), moderate dose of caffeine (5 mg/kg) and placebo (starch powder as capsules). Then, subjects performed tests of one-repetition maximum (1RM) for maximal strength, repetition to fatigue at 70% of 1RM for muscular endurance and number of repetitions in 15 seconds with 80% of 1RM for muscle power on the bench press (BP) and leg press (LP). The data were analyzed using analysis of variance (ANOVA) with repeated measures and dependent t test. The results showed that there was a significant increase (P<0.005) in maximal strength, muscular endurance and power for the moderate dose of caffeine group, but not for placebo and low dose of caffeine groups. It can be suggested that male body builders consume a moderate dose of caffeine one hour prior to exercise to improve their maximal strength, muscular endurance and power.