Pulmonary aspergillosis is a severe complication in heart transplant recipients. The drug of choice for this infection is amphotericin B, but its use is limited because of its side effects. We observed six cases of pulmonary aspergillosis in a group of 200 patients who had received heart transplants from January 1988 to January 1999. Predisposing factors such as previous rejection, neutropenia and/or cytomegalovirus reactivation were present in all patients. The clinical presentation was characterized by fever and a non-productive cough. X-rays showed monolateral or diffuse infiltrate with or without nodular lesions. The median interval between symptoms and diagnosis was 5 d (range 4-7). Diagnosis was made by culturing trans-tracheal aspirate samples. Aspergillus fumigatus was isolated in 3 patients and A. niger in the other 3. All patients were treated with itraconazole at 200-400 mg/day for 20-60 d and all recovered. One patient treated with the lowest dosage for the shortest term had a recurrence after 1 month and needed a second 30-day course of itraconazole at a higher dosage. No significant side effects were registered. Itraconazole is effective in the therapy of pulmonary aspergillosis, particularly when an early diagnosis is made.