Power athletes abuse anabolic androgenic steroids (AASs) and growth hormone (GH) to gain their muscular mass and strength. We wanted to determine how massive, self-administered doses of AASs with or without GH affect the left ventricular (LV) dimensions in power athletes. These substances are assumed to increase LVmass mainly by thickening the ventricular walls. Anecdotal evidence suggests a higher risk of cardiovascular events in AAS abusers. We were interested to see if LV dimensions and function in AAS abusers would indicate this increased risk. Twenty healthy male power athletes using massive doses of AAS without (n = 16) or with (n = 4) GH volunteered for the study. The controls were 15 sedentary male non-users of hormones. LV mass, geometry and filling were studied using standard echocardiographic methods. We found a significant association between LV mass and AAS dose (r = 0.54, p < 0.015). In contrast to the controls, LV mass (274 g in the athletes, 167 g in the controls) among the AAS abusers did not correlate with body weight or height. Concomitant use of AAS and GH further increased LV mass and associated with concentric remodelling of LV. Multiple regression analysis indicated that the mean AAS dose accounted for 29 %, age for 14 % and systolic blood pressure for 17 % of the variance in LV mass. We concluded that AAS abuse associates dose-dependently with myocardial hypertrophy and that concomitant use of GH associates with concentric remodelling of the LV. Our findings suggest that AASs and GH have a direct effect on the myocardium.