In 22 HIV positive patients a mild to moderate pneumocystis carinii pneumonia was treated by daily inhalation for 21 days of 600 mg pentamidine, divided into two inhalation phases with the inhalation of 300 mg pentamidin each. In 13 patients (59%) treatment was successful. In five cases, therapy was stopped in the first treatment week because of lacking clinical effectiveness resp. clinical deterioration. In four cases, therapy was discontinued in the further course. The subsequent treatment was successful in all cases. In the case of otherwise good tolerance, in two cases there was a hypoglycemia, in one case with clinical signs. In no case there was any sign of an extrapulmonary pneumocystosis.