To address the question of whether the increased plasma concentration of interleukin 6 (IL-6) following strenuous muscular work could be related to exercise-induced muscle damage, 5 moderately active male volunteers underwent two isokinetic exercise sessions in the eccentric mode, separated by a period of 3 weeks during which the subjects underwent five training sessions. Before training, exercise was followed by severe muscle pain (delayed-onset muscle soreness; DOMS), and by significant increases in plasma IL-6 level and serum myoglobin concentration (SMb) (P < 0.001). After training, postexercise DOMS and SMb values were significantly lower than those measured before training. There was no significant difference between plasma IL-6 levels measured at the same time points before and after training. We conclude that the hypothetical relationship between exercise-induced muscle damage and increased postexercise levels of circulating IL-6 is not substantiated by the present results.