Background. Dramatic increases in the number of patients requiring linkage to treatment for human immunodeficiency virus (HIV) infection are anticipated in response to updated Centers for Disease Control and Prevention HIV testing recommendations that advocate routine, opt-out HIV testing. Methods. A retrospective analysis nested within a prospective HIV clinical cohort study evaluated patients who established initial outpatient treatment for HIV infection at the University of Alabama at Birmingham 1917 HIV/AIDS Clinic from 1 January 2000 through 31 December 2005. Survival methods were used to evaluate the impact of missed visits during the first year of care on subsequent mortality in the context of other baseline sociodemographic, psychosocial, and clinical factors. Mortality was ascertained by query of the Social Security Death Index as of 1 August 2007. Results. Among 543 study participants initiating outpatient care for HIV infection, 60% missed a visit within the first year. The mortality rate was 2.3 deaths per 100 person-years for patients who missed visits, compared with 1.0 deaths per 100 person-years for those who attended all scheduled appointments during the first year after establishing outpatient treatment ( P = .02). In Cox proportional hazards analysis, higher hazards of death were independently associated with missed visits (hazard ratio, 2.90; 95% confidence interval, 1.28-6.56), older age (hazard ratio, 1.58 per 10 years of age; 95% confidence interval, 1.12-2.22), and baseline CD4+ cell count <200 cells/mm3 (hazard ratio, 2.70; 95% confidence interval, 1.00-7.30). Conclusions. Patients who missed visits within the first year after initiating outpatient treatment for HIV infection had more than twice the rate of long-term mortality, compared with those patients who attended all scheduled appointments. We posit that early missed visits are not causally responsible for the higher observed mortality but, rather, identify those patients who are more likely to exhibit health behaviors that portend increased subsequent mortality. © 2008 by the Infectious Diseases Society of America. All rights reserved.