The effects of protein supply and 1-carnitine were recorded in a group of junior elite cyclists by a prospective double blind placebo controlled trial for six weeks (Refit milk powder containing about 90% proteins and 5% mineral salts-Ca, P, K, Na and 1-carnitine tablets). Seven top junior cyclists received orally 1 g protein/kg.d as supplement of food for six weeks and 2 g 1-carnitine, also orally, per day, 10 days before an important competition; other 7 cyclists received the same regimen as placebo. Significant and favourable changes were recorded in the treated group for the strength index, lean body mass, fat mass, TWP (total work-kgm, performed on cycloergometer 1', serum proteins, serum Hb, serum calcium) changes which did not appear in the control group. Serum cholesterol, creatinine, thymol test and serum GPT did not change significantly in either group. All athletes were under medical supervision, had a controlled training programme and food and received daily only vitamins and mineral salts. The treated group supported better the stress-induced efforts and obtained higher performances in the international competition which took place at the end of the experiment. Based on these data the authors recommend a supply of protein ratio up to 3.2 g/kg.d, six weeks before competition and 2 g 1-carnitine daily, also orally, 10 to 14 days before competition, including the day of competition, for cyclists, in order to improve the biological potential of the body.