3 patients with severe CD4 lymphocytopenia (62-91 cells/microL) and inverted CD4/CD8 ratios (0.13-0.15) developed Pneumocystis carinii pneumonia during symptomatic, primary HIV-1 infection. Within four months of symptom onset, their CD4 counts and CD4/CD8 ratios returned to normal. Twenty-nine to forty-eight months after acquiring HIV-1 infection, they show no signs or symptoms of progression to AIDS. Pneumocystis carinii pneumonia can occur, therefore, in primary HIV-1 infection, and profound CD4 lymphocytopenia can revert to normal without antiretroviral therapy.