On the basis of studies with relatively short follow-up, treatment guidelines currently recommend that highly active antiretroviral therapy (HAART) be initiated in asymptomatic human immunodeficiency virus-infected patients when the CD4+ lymphocyte count is < or =200 cells/mm3. We assessed the development of a new opportunistic infection or death among 1173 patients initiating HAART. Durable virologic suppression was defined as having more undetectable (<400 copies/mL) than detectable virus loads after the initiation of therapy. The median durations of therapy and follow-up were 29 and 36 months, respectively. Among patients who achieved durable virologic suppression, those with baseline CD4+ lymphocyte counts of <200 cells/mm3 tended to progress faster than those with baseline CD4+ lymphocyte counts of 201-350 cells/mm3 (P=.09) and progressed faster than those with baseline CD4+ lymphocyte counts of >350 cells/mm3 (P=.01). Among those with durable virologic suppression, there was no difference in disease progression between those with baseline CD4+ lymphocyte counts of 201-350 cells/mm3 and those with durable virologic suppression with baseline CD4+ lymphocyte counts of >350 cells/mm3 (P=.40). Initiating HAART with a CD4+ lymphocyte count of <200 cells/mm3 was associated with a higher risk of disease progression, even with durable virologic suppression. HAART should be initiated at CD4+ lymphocyte counts of >200 cells/mm3.