Fourteen patients with postinfarctual ventricular aneurysm underwent equilibrium radionuclide angiocardiography at rest (ERNA) before and after oral digoxin administration in order to evaluate the effects of increasing myocardial contractility upon both ventricular aneurysm mechanical behaviour and global ventricular function. The ejection fraction (EF) was not significantly affected by digoxin therapy. However, digoxin induced changes in EF (ΔEF) correlated inversely with changes in aneurysm size and directly with changes in the extent of the hypokinetic area. Two types of aneurysm were observed: a) highcompliance aneurysm the size of which increased after digoxin administration while both EF and the extent of the hypokinetic area fell, and b) low compliance aneurysm for which opposite changes occurred. This different behaviour of ventricular aneurysm may have important practical implications as surgery would be probably more effective than medical treatment in improving resting ventricular function in patients with high-compliance aneurysm.