In order to verify the effects of oral Cr supplementation on performance, peak blood lactate (lac) levels and lean-fat body composition were determined for twelve young swimmers (15.1+1.1 years; 58.7+7.0 kg). Two groups were randomly assigned: supplemented group (SG, n=6) and control group (CG, n=6). For five days both groups received the following supplementation four times a day: 5g Cr + 50g of maltodextrine for SG and 50g of maltodextrine only for CG. The time and lac were measured before and after a five-day period of supplementation, and after a crawl-style swimming test: 1) 2x25m with 30-second rest, 2) 2x100m with 2-minute rest and 3) 1x700m trial. Bio impedance was applied for body composition, and sum of skin folds was determined before and after supplementation. Significant increase on the fat free mass of 1.0 (+0.4) kg with total body water retention of 1.5 (+0.5) liters was observed only for SG (p< .05). In fact, the increase in fat free mass may be due to the Cr-induced body water retention. No differences were found for the time and lac in aerobic and anaerobic exercises. We concluded that Cr supplementation for young swimmers (20g Cr/day for 5 days) increases fat free mass with no impact on performance.