The timing of the initiation of antiretroviral therapy in asymptomatic patients with HIV infection is unclear. In this retrospective study involving patients in North America from 1996 through 2005, the deferral of therapy until the patient's CD4+ count had fallen below one of the two thresholds of interest (a range of 351 to 500 cells or >500 cells per cubic millimeter) was associated with a relative hazard of death of 1.69 and 1.94, respectively. In this retrospective study involving patients in North America, deferral of therapy until the patient's CD4+ count had fallen below one of the two thresholds of interest (a range of 351 to 500 cells or >500 cells per cubic millimeter) was associated with an increase in the risk of death of 69% and 94%, respectively. The use of antiretroviral therapy has dramatically reduced disease progression and death among patients with human immunodeficiency virus (HIV) infection, 1 , 2 but the optimal time to begin therapy is uncertain. 3 , 4 Current guidelines recommend treatment for asymptomatic patients who have a CD4+ count of less than 350 cells per cubic millimeter on the basis of accumulating observational data. 5 , 6 However, these guidelines note the lack of data from randomized clinical trials regarding the timing of the initiation of antiretroviral therapy. 3 , 4 Data from randomized trials are limited to an analysis of a subgroup of 477 patients 7 from the Strategies for . . .