The aim of this study was to determine the effects of oral beta-hydroxy-beta-methylbutyrate (HMB) supplementation (3 g/d) on selected components of aerobic performance and body composition of active college students. Subjects were randomly assigned to either an HMB (n=8) or a placebo (PLA) group (n=8) for a 5-wk supplementation period during which they underwent interval training 3 times a week on a treadmill. Aerobic-performance components were measured using a respiratory-gas analyzer. Body composition was determined using dual-energy X-ray absorptiometry. After the intervention, there were significant differences (P<0.05) between the 2 groups in gains in maximal oxygen consumption (+8.4% for PLA and +13.4% for HMB). Regarding body composition, there were no significant differences. The authors concluded that HMB supplementation positively affects selected components of aerobic performance in active college students.