73-year-old man was admitted with a sudden onset of dyspnea. He had never smoked. The chest radiograph and computed tomography revealed bilateral ground glass opacity and an enlarging perihilar consolidation with lymphadenopathies. There was a higher percentage of eosinophils (72%) in the bronchoalveolar lavage fluid (BALF) than normal. The patient was diagnosed with acute eosinophilic pneumonia and managed with steroid. Pneumocystis pneumonia (PCP) was diagnosed by an examination of the BALF, and the patient was treated with trimethoprim-sulphamethoxazole. The patient tested positive to the HIV antibody and the peripheral blood CD-4 positive lymphocyte count was only 33/microliter. The percentage of eosinophils in the BALF can increase in some cases of PCP that is complicated with AIDS. Only a few cases of eosinophilic pneumonia associated with PCP pneumonia have been reported in patients with AIDS but there are no case reports in Korea. This case highlights the need to consider PCP when the percentage of eosinophils in the BALF is elevated.