We compared clinical disease progression in 159 human immunodeficiency virus (HIV)-infected persons for whom highly active antiretroviral therapy (HAART) was initiated when they had CD4(+) T lymphocyte counts of 350-499 cells/mm(3) with progression in 174 HIV-infected patients for whom it was not. Disease progression did not differ between the 2 groups (P=.21, log-rank test). Fifty-three percent of the 159 treated patients had HIV type 1 RNA levels of >400 copies/mL at the most recent evaluation, and 41% had experienced adverse drug reactions necessitating a change in regimen. These findings support the recommendation that HAART not be initiated for patients with CD4(+) cell counts of >350 cells/mm(3).