Interstitial pneumonitis, often related to infectious etiologies, occurs commonly in HIV-infected patients. However, hypersensitivity pneumonitis from noninfectious etiologies, including environmental stimuli or drug exposure, is an unusual etiology of interstitial pneumonitis in HIV-infected patients. We report a patient with AIDS who developed a dapsone-induced hypersensitivity pneumonitis mimicking Pneumocystis carinii (PCP) pneumonia. We believe drug-induced hypersensitivity pneumonitis should be considered in the differential diagnosis of interstitial pneumonia in HIV-infected patients in whom infectious etiologies have been ruled out.