The late cardiac effects of anterior mediastinal irradiation were assessed in 15 patients, 5-15 years after radiation therapy for Hodgkins disease. Diminished left ventricular ejection fraction (determined by ECG gated Tc99m left ventricular cineangiography) with exercise was present in 1/15 (33%) of patients; average ejection fraction at exercise was also below normal for the group. Pericardial effusion on echocardiogram was present in 40% of patients. Asymptomatic impairment of systolic left ventricular function and pericardial effusion may be commonly present many years after mediastinal irradiation for Hodgkins disease.