OBJECTIVE: To compare the changes in cardiorespiratory and muscular fitness, and the changes in physical self-concept after participation in one of two psychomotor therapy programmes in a sample group of psychiatric patients. To study the relationship between the changes in physical fitness and the changes in physical self-concept. DESIGN: Randomized controlled parallel-group trial with repeated measures. SETTING: Three treatment units of a university psychiatric hospital in Belgium. SUBJECTS: One hundred and ninety-nine patients with severe symptoms of depression and/or anxiety, and/or personality disorders. INTERVENTIONS: A general programme of psychomotor therapy, consisting of different forms of physical exercises and relaxation training, and a personalized psychomotor fitness programme, consisting of aerobic and resistance training. These programmes were followed three times a week for a period of 16 weeks. OUTCOME MEASURES: The maximum dynamic strength, the strength endurance, physical work capacity at 60% and 80% of the estimated maximal heart rate reserve, and the physical self-concept by means of the Dutch version of the Physical Self-Perception Profile. RESULTS: After eight weeks, both groups exhibited an improvement in muscular fitness (both p-values < 0.0001), but only the psychomotor fitness group had improved in cardiorespiratory fitness (p < 0.01). After 16 weeks, the patients in the general programme of psychomotor therapy had not increased in cardiorespiratory fitness. At the end of the 16-week programmes, both groups showed a more positive physical self-concept (p from 0.01 to < 0.0001). However, these improvements were not related to the progress in physical fitness. CONCLUSIONS: The main difference in the effectiveness of the two programmes was the increase in cardiorespiratory fitness in the psychomotor fitness group. The gains in fitness did not play an essential role in the enhancement of physical self-concept.