We retrospectively evaluated the effectiveness of nevirapine-containing regimens in 118 naive patients initiating highly active antiretroviral therapy with CD4 cell counts S 200 cells/jl. After 24 months, 51% of patients continued nevirapine, 43 and 83% had viral loads < 50 copies/ml by intent-to-treat and on-treatment analyses, and a mean increase of +246 CD4 cells/microl occurred. More than 80% of patients who continued with nevirapine had viral loads < 50 copies/ml and CD4 cell counts > 200 cells/pl.