The spectrum of acute renal failure is different in intensive care unit (ICU) vs. non-ICU population. This one year prospective study carried out in medical and surgical intensive care units showed an incidence of 8.6% of acute renal failure. The incidence of acute renal failure was highest in medical ICU (17.2%) followed by burns ICU (5.3%), pulmonary ICU (5.2%), stroke ICU (4.4%), surgical ICU (3.1%) and least in coronary ICU (1.3%). The acute renal failure was attributable to medical causes in 68% followed by surgery and trauma in 21.2%, burns in 5.6% and pregnancy related in 5.1%. In majority, acute renal failure was multifactorial. Septicemia was the commonest cause in both medical (50%) and surgical (86%) ICUs. Multi organ system failure was present in 77.3% of patients with acute renal failure. Approximately 40% required dialysis. The mortality of acute renal failure was 62% and the mortality was correlated with the number of organ system failures, presence of oliguria and septicemia. The mean ICU stay was significantly shorter in the non-survivors.