Renal failure remains a serious cause of mortality in Yemen. Our region has 1.25 million population and our hospital is the central hospital, which has a nephrology department and performs dialysis for the region. Between January 1998 and December 2002, we admitted 547 patients; including children, with acute renal failure (ARF) and chronic renal failure (CRF). CRF was observed in 400 patients, an incidence of 64 per million per year and a prevalence of 320 per million. ARF occurred in 147 persons with an incidence of 23.5 per million per year and a prevalence of 117.5 patients per million. Of all patients, 72% were adults (age range, 20-60 years) with a male preponderance. As a tropical country, malaria (27.9%), diarrhea (13.6%), and other infectious diseases were the main causes. Next most common were obstructive diseases causing CRF and ARF (26.8% and 12.9%, respectively), mainly urolithiasis, Schistosomiasis, and prostatic enlargement. However the cause of CRF in 57.5% of patients was unknown as most persons presented late with end-stage disease (64.7%), requiring immediate intervention. Other causes, such as hepatorenal syndrome, snake bite, diabetes mellitus, and hypertension, showed low occurrence rates. Patients presented to the hospital mostly in severe uremia and without a clear history of prior medications. The major findings were vomiting, acidosis, and hypertension with serum creatinine values ranging between 2.8-45 mg/dL (mean value, 13.4 mg/dL). Anemia was observed in 80.4% of CRF versus 62.6% of ARF patients. Hypertension prevalence was 65.5% among CRF patients, of whom 25% were in hypertensive crisis, whereas among ARF the prevalence was only 26.5%.