Abstract Increased blood levels of branched chain amino acids (BCAAs) have been associated with cardiometabolic risk factors. Here, we studied 918 community-dwelling older men to determine the relationship between BCAAs and other amino acids with cardiometabolic risk factors, major cardiovascular endpoints (MACE), and mortality. BCAAs had robust associations with many adverse metabolic risk factors (increased glucose, insulin, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), triglycerides; decreased high-density lipoprotein cholesterol). However, paradoxically, participants with lower levels of BCAAs had greater mortality and MACE possibly because increasing age and frailty, both of which were associated with lower BCAA levels, are powerful risk factors for these outcomes in older people. Overall, amino acids that were lowest in frail subjects (BCAAs, α-aminobutyric acid [AABA], histidine, lysine, methionine, threonine, tyrosine) were inversely associated with mortality and MACE. In conclusion, BCAAs are biomarkers for important outcomes in older people including cardiometabolic risk factors, frailty, and mortality. In old age, frailty becomes a dominant risk factor for MACE and mortality.