Although human immunodeficiency virus-infected people aged > or =50 years have a blunted CD4 cell recovery when receiving highly active antiretroviral therapy (HAART), there are few data on mortality. Mortality rates were studied for 253 individuals aged > or =50 years and a younger group of 535 people in a retrospective cohort; for untreated persons in each age group, the proportions surviving at 3 years were 83% and 70% (P<.01), respectively. No significant difference in the survival rate was found between the older (83%) and younger (89%) patients who received HAART (P=.29). The hazard ratio for death in the older untreated group was 2.4 (95% confidence interval [CI], 1.4-3.9) when exposed to HAART. However, compared with older untreated patients, the hazard ratio for death decreased to 0.28 (95% CI, 0.15-0.52) for treated older adults. The effect of HAART substantially improves the survival rate for older individuals and supports the importance of treatment in this group.