The present study focuses on the role of branched-chain amino acids (BCAA) (leucine, isoleucine and valine) in cancer cachexia. This is a frequent and devastating complication of cancer occurring in more than two thirds of patients who die with advanced cancer, and in up to 22% of cancer deaths it is the only abnormality found at autopsy. BCAA are essential amino acids often increased in cancer patients and this phenomenon may be related with increased protein degradation in skeletal muscle and consequently, cancer cachexia. The relevance of this association in medical terms is evident, future investigations may focus on therapeutical strategies based on the administration of BCAA to cachectic patients.