INTRODUCTION: It is not uncommon for patients with HIV infection to miss scheduled visits in outpatient clinics without justifying the failure to appear or reschedule the appointment. Few studies have assessed the impact of inconsistent follow-ups on resource use and disease outcomes in this patient population. OBJECTIVE: To assess the effect of missing scheduled visits to the outpatient clinic on the health outcomes of HIV-infected patients. METHODS: Between January and June 2006, we conducted a prospective observational study monitoring assistance at an outpatient HIV/AIDS clinic of a tertiary hospital within a public health care system in a developed country. The short-term subsequent events (deaths and admissions) of the population were observed from January to December 2006. RESULTS: Of the 1,733 HIV patients who were scheduled in the outpatient clinic, 103 met the criteria of missing scheduled visit (5.9%). Hospital admissions and mortality rates were significantly higher in the missing scheduled visit group compared to non-missing scheduled visits (27.2% vs 8.9%; P < .001 and 5.8% vs 0.7%; P < .001, respectively). Patients with missing scheduled visits had a higher risk of hospital admissions (odds ratio [OR] 2.4; 95% CI, 1.4-4) and mortality (OR 6.7; 95% CI, 2.2-18.5) adjusted by age, CD4 cell count, HIV stage, and category of transmission. CONCLUSIONS: Missing scheduled visits was an independent predicting factor for hospital admission and mortality. It is warranted to monitor and implement resources to reduce missed appointments.