To determine the frequency and severity of clinically unrecognized left ventricular (LV) dysfunction related to cocaine use, 84 asymptomatic cocaine abusers underwent cardiac evaluation which included chest x-ray, electrocardiography (ECG), and radionuclide angiography after a two-week abstinence from cocaine use. LV dysfunction was discovered in 6/84 (7%). Regional wall motion abnormalities suggesting a localized myocardial abnormality were found in 2, whereas an ejection fraction less than 50% suggesting a more global process was noted in 4. An abnormal chest x-ray was found in only 1 subject and none had abnormal ECGs. In each of these cases, repeated and protracted use of cocaine was documented and the suggestion of cardiac dysfunction was supported by at least one other independent abnormal finding. In these 6 cases, the dysfunction was clinically unrecognized and unsuspected after routine evaluation. The significance of subclinical LV dysfunction in this population has not been determined and requires long-term study.