Three patients had a typical clinical, functional, and histologic pattern of lymphoid interstitial pneumonitis (LIP). All 3 also had a marked follicular and interfollicular hyperplasia of peripheral lymph nodes. A benign lymphocytic infiltration was seen in the kidneys in 2 patients, in the liver of 1 of these, and in the nasopharynx and the bone marrow in another. This LIP, associated with other diffuse benign lymphocytic infiltrates, could be part of AIDS-related manifestations. The patients originated from central Africa (2 patients) and Haiti (1 patient) where AIDS is endemic. They had several immune abnormalities frequently observed in AIDS such as a polyclonal hyperimmunoglobulinemia and, in the 2 patients studied, a decreased number of T4 lymphocytes and an inverted T4/T8 blood lymphocyte ratio. All 3 patients had serum antibodies to human T-cell leukemia viruses.