To analyze the impact of highly active antiretroviral therapy on lymphoid interstitial pneumonia (LIP), we reviewed the medical files of 5 human immunodeficiency virus (HIV)-infected patients in whom LIP was diagnosed during 1996-2001 who had never previously received antiretroviral treatment. Patients were mildly immunosuppressed at the time of diagnosis of LIP but had high plasma HIV loads and marked circulating and pulmonary CD8 hyperlymphocytosis. All patients improved clinically, radiologically, and functionally; improvement was accompanied by a drastic reduction in the virus load and an increase in the CD4 lymphocyte count.