A 60-year-old man was admitted to our hospital complaining of non-productive cough. He had worked in Africa and received a blood transfusion after a traffic accident in 1985. On admission, the patient had remarkable hypoxemia and a decreased CD4+ lymphocyte count. A serological test for human immuno-deficiency virus (HIV)-1 was positive. His chest radiographs showed diffuse reticular and linear opacities, and broncoalveolar lavage findings established a diagnosis of Pneumocystis carinii pneumonia (PCP). A high-resolution CT of the chest revealed peripheral infiltrates and low attenuation areas (LAA) consistent with severe emphysematous alterations. We administered high-dose methylprednisolone and trimethoprim-sulphamethoxazole (TMP-SMX). Because of marked eosinophilia, TMP-SMX was discontinued, and the patient was given inhaled pentamidine isothiocyanate. Although there was a striking clinical improvement, the emphysema-like lesion on chest CT remained unaltered. LAA on CT had been modest in 1994, but had markedly enlarged during the three years thereafter, leading us to speculate that most of the LAA lesions recognized on admission might have developed in association with PCP. Pulmonary function tests showed an obstructive ventilatory defect and impaired diffusing capacity. Although PCP classically presents with diffuse ground-glass or fine granular opacities, thin-walled cavities or other atypical findings have recently been reported, especially in AIDS patients. There have been several reports about emphysema-like lesions associated with PCP. It was suggested that these lesions might be due to lung parenchyma destruction induced by HIV itself or increased elastase release from HIV-infected macrophages. This is the first report of PCP with pulmonary emphysematous lesions in Japan.