The cost of treating end-stage renal failure (ESRF) patients includes not only the cost of dialysis and related medications but also the cost of hospitalizing these patients. This study examines the hospitalization rate in ESRF patients. During 1993, 126 ESRF patients were dialyzed in our institution. All hospitalizations were recorded. The study included 213 hospitalizations in 91 patients (mean 1.7 hospitalizations/patient/year). The mean length of each hospitalization was 4.8 +/- 5.6 days. Seventy-six hospitalizations were for 1 day. Access (vascular and peritoneal) was the main cause (31%), but these admissions accounted for only 8.7% of days in hospital, while cardiovascular and infections represented 38 and 29%, respectively. No correlation was found between type of dialysis, sex and erythropoietin use and hospitalization rate. 46.5% of admissions were uremia-dialysis related but they accounted for only 30% of the days in hospital. Age and the presence of diabetes mellitus correlated with hospitalization not related to uremia and/or dialysis. Thus, most of the time spent in hospital was secondary to conditions unrelated to uremia and/or dialysis. Efforts should be made to reduce the dialysis-uremia-related hospitalizations and thus reduce the cost of treatment.