The aim of this work was to examine the effect of culturistic training and oral supplementation with L-carnitine on sports results, body make-up, aerobic and anaerobic efficiency, lipids and anti-oxidative enzymes in blood. The testing was conducted before and after a 5-week long culturistic training of young males. One of the groups, chosen at random, was administered L-carnitine in a dose recommended by the producer (11.5 mg for 1 kg of body mass), the other group received placebo. It was stated that oral supplementation with L-carnitine increased the training effects in the form of force growth and force endurance, other assayed parameters did not show significant differences.