PURPOSE To compare the acute effect of caffeine ingestion on performance in young judo athletes. METHOD In a randomized double-blind design, eighteen judo athletes (16.1 ± 1.4 yrs.) were evaluated on three nonconsecutive days. On the first day, the special judo fitness test (SJFT) was used as a control session. On the second day, the sample was randomly divided into two equal groups. One group received 4 mg.kg-1 of caffeine (capsule) and the other group received a placebo. After resting for 60 min, the sample performed the SJFT. On the final day of testing, the same procedure was performed but the substance ingested was exchanged between the groups. RESULTS Heart rate (HR) and rating of perceived exertion (RPE) were recorded throughout the applications of the SJFTs. Caffeine ingestion did not induce changes in HR, but reduced the RPE compared with the placebo session (7.0 ± 1.1 vs 8.2 ± 2.0; p < .05), increased the number of throws applied (29.0 ± 2.6 vs 22.1 ± 3.4; p < .01) and reduced the SJFT index (12.2 ± 0.5 vs. 15.7 ± 0.9; p < .001). CONCLUSION 4 mg.kg-1 did not alter HR but improved performance on SJFT in young judo athletes and reduced the RPE.