PURPOSE: Androgen deprivation therapy (ADT) for prostate cancer has multiple adverse effects on musculoskeletal health. This 12-month randomized controlled trial aimed to assess the effects of multicomponent exercise training combined with whey protein, calcium and vitamin D supplementation on bone mineral density (BMD), structure and strength, body composition, muscle strength, and physical function in ADT-treated men. METHODS: Seventy ADT-treated men were randomized to exercise plus supplementation (Ex + Suppl; n = 34) or usual care (control; n = 36). Ex + Suppl involved thrice weekly progressive resistance training plus weight-bearing impact exercise with daily multinutrient supplementation. Primary outcomes were DXA hip and spine areal BMD. Secondary outcomes included the following: tibia and radius pQCT volumetric BMD, bone structure and strength, DXA body composition, pQCT muscle and fat cross-sectional area and muscle density, and muscle strength and physical function. RESULTS: Sixty men (86%) completed the study. Mean exercise and supplement adherence were 56% and 77%, respectively. There were no effects of the intervention on bone or body composition outcomes. Ex + Suppl improved leg muscle strength (net difference, (95% confidence interval, or CI), 14.5% (-0.2 to 29.2); P = 0.007) and dynamic mobility (four-square-step test time, -9.3% (-17.3 to -1.3), P = 0.014) relative to controls. Per-protocol analysis of adherent participants (≥66% exercise, ≥80% supplement) showed Ex + Suppl preserved femoral neck aBMD (1.9% (0.1 to 3.8), P = 0.026) and improved total body lean mass (1.0 kg (-0.23 to 2.22), P = 0.044) relative to controls. CONCLUSIONS: Exercise training combined with multinutrient supplementation had a limited effect on ameliorating the adverse musculoskeletal consequences of ADT, likely related to the modest intervention adherence.