This study reports on a first case of granulomatous Pneumocystis carinii pneumonia (PCP) in a human immunodeficiency virus-negative patient with antineutrophil cytoplasmic antibody-positive Wegener's granulomatosis whilst receiving immunosuppressive treatment. The patient presented with diffuse alveolar haemorrhage, pauci-immune rapid progressive glomerulonephritis and leukocytoclastic vasculitis of the skin. Granulomatous Pneumocystis carinii pneumonia developed under immunosuppressive treatment with cyclophosphamide and prednisone. At the time Pneumocystis carinii pneumonia developed, there was a marked lymphopenia with a very low CD8+ cell count in the blood. Grocott staining in bronchoalveolar lavage fluid revealed no Pneumocystis carinii. The diagnosis was made via a video-assisted thoracoscopic lung biopsy which showed granulomas containing high numbers of Pneumocystis carinii cysts.