Primary infection with the human immunodeficiency virus (HIV-1) has been associated with a self-limited illness resembling acute infectious mononucleosis. Pulmonary manifestations have been notably absent in published reports. The authors describe a 28-year-old homosexual male who presented with primary HIV-1 infection associated with CD8+ lymphocytic alveolitis. Diagnosis was delayed because HIV antibody was not detected by the Abbott ELISA, although the same and subsequent specimens were later found to be positive by Genetic Systems' ELISA and Western blot analysis. Lymphocytic alveolitis must be added to the expanding clinical spectrum of acute HIV-1 infection. The time to detection of seroconversion may vary with different immunoassays.