Day care units have become an usual way of medical care for AIDS patients. However, their influence on the incidence of hospital admissions has not been evaluated. METHODS: Observational and longitudinal study of a cohort of 308 patients with aids diagnosed between 1990 and 1994 and followed-up to June 1996. The incidence of hospital admissions according to the hospital of follow-up (with or without day care unit) was analyzed. A multivariate analysis of the number of hospital admissions was performed using regression model adjusted to a distribution of Poisson. RESULTS: After AIDS diagnosis, the incidence of hospital admissions was 108 per 100 patient-years of follow up (21 days as inpatient per patient-year). Those patients controlled in the hospital with day care unit have less hospital admissions (relative risk after adjusting by CD4+ cells count and type of diagnostic disease: 0.64; CI95% 0.55-0.76), and less days as inpatient through their follow-up (11 to 31 days less). There was no difference in survival among patients followed in both hospitals. CONCLUSIONS: A day care unit decrease the incidence of hospital admissions in aids patients. This positive impact is more evident in patients with lesser CD4+ cell counts. ; SIN FINANCIACIÓN ; 0.750 JCR (2000) Q2, 42/105 Medicine, General & Internal ; UEM