To determine whether CD4 cell count response to virus suppression during highly active antiretroviral therapy differs according to sex or race/ethnicity, we analyzed data in our observational cohort study for patients receiving their first antiretroviral regimen who experienced virus suppression by 6 months of therapy. In both univariate and multivariate analyses, women had greater CD4 cell count increases, compared with men, as did patients receiving a regimen that did not include a protease inhibitor. Race/ethnicity was not a factor.