The aim of this study was to examine whether lung function and respiratory muscle strength are associated with weightlifting strength and body composition in non-athletic males. A total 51 males with resistance training experience participated. One-repetition maximum tests were performed for the bench press, squat and deadlift and body composition was assessed. Lung function was evaluated with a pulmonary testing system and respiratory muscle strength was assessed with a handheld mouth-pressure manometer. Moderate to strong positive relationships were found between all weightlifting strength variables and maximal expiratory pressure (r = 0.36-0.54, p = ≤0.01). Small to strong positive correlations were found between fat-free mass, appendicular lean mass and most lung function variables (r = 0.29-0.54, p ≤ 0.039). However, fat-free mass and appendicular lean mass indexes were only related with respiratory muscle strength and not lung function. Expiratory muscle strength appears to influence weightlifting performance. Special exercises targeting the expiratory muscles may assist with improving weightlifting performance, especially for squats and deadlifts.