Amiodarone, a new antiarrhythmic drug, may produce severe and potentially lethal pulmonary toxicity. A case is presented of a patient on amiodarone therapy who presented with recurrent pleural effusions and subsequently developed pulmonary infiltrates. The diagnosis of lung toxicity was documented by the cytologic examination of the pleural effusions and the bronchial washings. It was further supported by the ultrastructural demonstration of the characteristic cytoplasmic osmiophilic lamellar inclusions in the foamy macrophages. We conclude that cytologic and ultrastructural examinations of bronchial lavage cells are extremely helpful in the diagnosis of amiodarone-induced pulmonary toxicity.