The purpose of the study was to determine the effect of anti-inflammatory doses of ibuprofen on neutrophils, neutrophil O-2(-) production, and markers of muscle injury. Males (n = 10) performed 2 bouts of one-arm eccentric exercise on opposite arms separated by three weeks. Subjects received 2400 mg . d(-1) of ibuprofen or a placebo 5 d before exercise and during 10 d of recovery. Measurements were made before the treatments, pre-exercise, at 4 h, and at 1, 2, 3, 4 and 10 d postexercise. Circulating neutrophil counts were similar between the treatments at the sampling points. Neutrophil counts were higher (p < 0.05) for ibuprofen and were elevated (p < 0.05) at 4 h post-exercise relative to pre-exercise in both treatments. Stimulated neutrophil O-2(-). production was lower for ibuprofen relative to placebo at pre-exercise and was increased (p < 0.05) at 4 h and 4 d of both treatments. CK activity at 3 d post-exercise was tower (p < 0.05) for ibuprofen relative to placebo. Isometric strength, soreness, tenderness, and arm angles were similar between the treatments. In conclusion, anti-inflammatory doses of ibuprofen reduced CK activity but not the neutrophil response or other indirect markers of muscle injury during recovery from eccentric arm exercise.