A 79-year-old female was admitted to our hospital because of a malignant pleural effusion following mastectomy 4 years ago. In the patient's history arterial hypertension and previous inferior myocardial infarction have been known. Two doses of 20 mg mitoxantrone were installed intrapleurally at an interval of 4 weeks. Six hours after the second mitoxantrone application and the patient had increasing dyspnea with consecutive left heart failure, pulmonary congestion, and a drop of blood pressure. The white-cell count was 14800/mm3. The levels of creatinine phosphokinase (CPK), lactate dehydrogenase (LDH) and serum aspartate aminotransferase (SGOT) were in the normal range. Transthoracic echocardiography showed concentric left ventricular hypertrophy and a markedly decreased fractional shortening, but no left ventricular dilatation. The electrocardiogram showed newly appeared down-sloping ST-segments and inverted T-waves. Clinical recovery was achieved after 6 days by application of oxygen, dobutamine and furosemide followed by angiotensin converting enzyme inhibition and digitalis. In the echocardiographic control examination 14 days later left ventricular function had normalized. The changes of electrocardiogram normalized 4 weeks later.