The purpose of the present study was to examine the duration of caffeine's ergogenic effect and whether it differs between users and non-users of the drug. Twenty-one subjects (13 caffeine users and 8 non-users) completed 6 randomized exercise rides to exhaustion (ER) at 80%VO_2max after ingesting either a placebo or 5 mg/kg of caffeine. ER was completed once per week at either 1, 3 or 6 hours after placebo or drug ingestion. Exercise time to exhaustion differed between users and non-users with the ergogenic effect being greater and lasting longer in non-users. For the non-users, exercise times 1, 3 and 6 hours after caffeine ingestion were 32.7 ± 8.4, 32.1 ± 8.6 and 31.7 ± 12.0 min, respectively, and these values were each significantly greater than the corresponding placebo values of 24.2 ± 6.4, 25.8 ± 9.0 and 23.2 ± 7.1 min. For caffeine users, exercise times 1, 3 and 6 hours after caffeine ingestion were 27.4 ± 7.2, 28.1 ± 7.8 and 24.5 ± 7.6 min, respectively. Only exercise times 1 and 3 hours following drug ingestion were significantly greater than the respective placebo trials of 23.3 ± 6.5, 23.2 ± 7.1 and 23.5 ± 5.7 min. In conclusion, both the duration and magnitude of the ergogenic effect that followed a 5 mg/kg dose of caffeine was greater in the non-users compared to the users.