To ascertain the effect of anabolic steroids (AS) on left ventricle size and function, M-mode and 2D echocardiographic evaluation was carried out in 14 body builders at the end of a phase of AS self-administration (8 +/- 3 weeks, mean +/- S.D.) and after a period (9 +/- 2 weeks, mean +/- S.D.) of drug withdrawal, as well as in 14 other body builders who had never made use of AS, and in 14 sedentary individuals. All the subjects were also examined anthropometrically. Ventricular septal thickness index was slightly greater in athletes using AS, compared to the other two groups (p less than 0.05), while left ventricle mass, the end-diastolic volume indexes and isovolumetric relaxation time, (a parameter of left ventricle diastolic function) were significantly increased (p less than 0.001) as well as the fat free mass (FFM), a marker of skeletal muscle mass. The non-users showed no differences in echocardiographic parameters, compared to sedentary controls. During the off treatment phase, the percentage of adipose mass increased and FFM decreased, while echocardiographic parameters did not vary significantly from on treatment values. The findings indicate that AS can induce an unfavourable enlargement and thickening of the left ventricle, which loses its diastolic properties with the mass increase. These modifications tend to persist following a short period of drug withdrawal.