This publication is the International Society of Sports Nutrition position stand on the efficacy of HMB use in sports nutrition and combines a comprehensive review of HMB with the official position of the ISSN on HMB use.  The position statements included in this paper were reviewed and approved by the Research Committee of the ISSN. Based upon this comprehensive review of HMB literature, the primary position statements were that HMB enhances muscle recovery by attenuating muscle damage; HMB increases muscle hypertrophy, strength, and power in trained and untrained populations when the appropriate exercise protocol is applied; HMB efficacy is manifested in young and old; and HMB is safe to consume.