There were 19 males and 11 females with a mean age of 21 +/- 3 years and a mean weight of 72.8 +/- 3.2 kg who participated in an experiment to investigate the effect of caffeine on simple reaction time (RT) and movement time (MT). Subjects were randomly assigned to one of three groups--two experimental groups and one control group. Caffeine was administered using a double-blind format: Group 1, 600 mg caffeine; Group 2, 300 mg caffeine. Group 3, the control group, was given a placebo. All subjects were pre-tested for RT and MT prior to consumption of one of the three solutions. Post-test was conducted subsequent to an absorption period of 45 min. Results indicated a significant effect (p less than 0.05) between pre- and post-test measurements for both RT and MT favoring the 300 mg group. However, no significant effect (p greater than 0.05) was found between pre- and post-test measurements for RT or MT in the 600-mg group.