Limited data suggests that consumption of fluid milk following resistance training may promote skeletal muscle hypertrophy. The aim of this study was to assess whether a milk-based nutritional supplement could enhance the effects of resistance training (RT) on muscle mass, size, strength and function in middle aged and older men. This was an 18-month factorial design RCT in which 180 healthy men aged 50-79 years were allocated to: (1) exercise+fortified milk; (2) exercise; (3) fortified milk; or (4) controls. Exercise consisted of progressive RT with weight-bearing impact exercise. Men assigned to the fortified milk consumed 400mL/d of low fat milk providing an additional 836 kJ, 1000mg calcium, 800IU vitamin D3 and 13.2g protein per day. Total body lean mass (LM) and fat mass (FM) (DXA) and mid-femur muscle cross-sectional area (CSA) (QCT), muscle strength and physical function were assessed. After 18-months, there was no significant exercise-by-fortified milk interaction for total body LM, muscle CSA or any functional measure. However, main effects analyses revealed that exercise significantly improved muscle strength (~20-52%, p<0.001), LM (0.6 kg, p<0.05), FM (-1.1 kg, p<0.001), muscle CSA (1.8%, p<0.001), and gait speed (11%, p<0.05) relative to no-exercise. There were no effects of the fortified milk on muscle size, strength or function. In conclusion, daily consumption of low fat fortified milk does not enhance the effects of resistance training on skeletal muscle size, strength or function in healthy middle aged and older men with adequate energy and nutrient intakes.