The relationship between the pattern of virus load response to highly active antiretroviral therapy (HAART) and CD4 lymphocyte response was assessed in a cohort of 249 human immunodeficiency virus (HIV) type 1-infected women at 3 times: 1 before and 2 after initiation of therapy, with follow-up of 6-12 months. Patients with a durable response to HAART (i.e., >1 log decrease in HIV-1 RNA sustained for the study periods) had a continuous and significant increase in CD4 cell counts over time, whereas those with no response (<0.5 log decrease in HIV-1 RNA) had a slight decline. Patients with a mixed response (initial decrease >1 log, followed by a subsequent decrease <0.5 log) had an increase in CD4 cell count, followed by a plateau. The trend in CD4 cell count differed significantly by response to HAART, with those patients who experienced a durable response having significantly higher CD4 cell counts than others.