A 39-year-old man with AIDS presented with acute respiratory distress and diffuse bilateral infiltrates seen on a chest radiograph. Acute eosinophilic pneumonia (AEP) was diagnosed by thoracoscopic lung biopsy. There was no evidence of an infectious etiology, and the patient rapidly improved with corticosteroid therapy. Several of the idiopathic interstitial pneumonias have been reported in adult patients with AIDS. To our knowledge, this case represents the first tissue-confirmed case of AEP associated with adult AIDS.