OBJECTIVES. The objectives of this study were to review the prevalence, cause, and morbidity and mortality rates of acute renal failure in a large tertiary care institution in southern Thailand, to examine any differences in acute renal failure cases diagnosed during a 22-year period, and to determine the risk factors indicating death. METHODS. The case records for children 1 month to 17 years of age who were diagnosed as having acute renal failure between February 1982 and December 2004, in the Department of Pediatrics, Songklanagarind Hospital, in southern Thailand, were reviewed. RESULTS. A total of 311 children with 318 episodes of acute renal failure were included, that is, 177 boys (55.7%) and 141 girls (44.3%), 1 month to 16.7 years of age (mean age: 7.6 ± 5.1 years; median age: 7.8 years). The causes of acute renal failure in each age group were significantly different. Overall, sepsis was the major cause of acute renal failure, accounting for 68 episodes (21.4%), followed by hypovolemia, poststreptococcal glomerulonephritis, systemic lupus erythematosus, and infectious diseases. Renal replacement therapy was performed in 55 cases (17.3%). The overall mortality rate was 41.5%. Logistic regression analysis showed that disease groups and creatinine levels were significant independent predictors of outcomes. CONCLUSIONS. The incidence of acute renal failure in Songklanagarind Hospital was 0.5 to 9.9 cases per 1000 pediatric patients, with a mortality rate of 41.5%. Sepsis was a major cause of acute renal failure and death. Causes of acute renal failure and serum creatinine levels were significant independent predictors of death.