The records of 563 patients admitted to the hospital with diagnosis of acute pancreatitis have been studied retrospectively. The aim of the study was to investigate the prevalence of acute renal failure (ARF) in these patients, and to evaluate the most important risk factors for ARF development and mortality. The prevalence of ARF in studied population was 14%, but only 3.8% of ARF patients with acute pancreatitis had isolated renal failure. Other patients had additional failure of other organ systems, 68.4% of whom had multiorgan failure (MOF) before the onset of ARF. In only 8.9% of ARF patients was the renal system the first organ system to fail. Patients with ARF were significantly older, had more preexisting chronic diseases (including chronic renal failure), usually had MOF, and local pancreatic complications relative to these in the group with normal renal function. The development of ARF was directly influenced by severity of acute pancreatitis. The mortality rate in ARF patients was 74.7%, compared to an 7.4% mortality of patients with acute pancreatitis and normal renal function. Preexisting chronic disease, the presence of MOF and their number, local pancreatic complications, and older age of the patients increased mortality in ARF patients. The prognosis of patients with oliguric ARF requiring renal replacement therapy was extremely poor, indicating the importance of prevention of ARF in the patients with acute pancreatitis.