Background/Aims: Review of bone marrow transplant (BMT) cases admitted to our intensive care unit (ICU) and to compare co-morbidity and outcome of BMT patients developing or not developing acute renal failure (ARF). Methods: A case review of BMT patients admitted to the ICU (a 16-bed medico-surgical ICU in a tertiary care teaching institution) over a 4-year period. Results: Between January 1994 and December 1998, 57 among 441 BMT patients (12.9%) were admitted to the ICU, mainly for respiratory distress (58%) and hypotension (32%). Forty-two patients (73.7%) presented ARF as defined as a doubling of serum creatinine. Compared to the 15 other patients, ARF patients had a higher APACHE II score (30 ± 8 vs. 25 ± 7, p < 0.05). For ARF vs. non-ARF patients, there was no difference in age (43.8 ± 10.8 vs. 44.3 ± 11.1 years), in requirement for mechanical ventilation (76 vs. 73%) and vasopressors (69 vs. 60%), and in prevalence of graft-versus-host disease (19 vs. 13%) or neutropenia (69 vs. 67%), but the prevalence of sepsis (83 vs. 60%) and liver failure (69 vs. 40%) was higher. Maximum serum bilirubin was markedly increased in ARF compared to non-ARF patients (p < 0.005). For both subgroups, no difference in the administration of potential nephrotoxic agents was identified. Usually, ARF was considered multifactorial by clinicians, with ATN being the most frequent diagnosis (55%). Maximum serum creatinine reached a mean of 330 ± 130 µmol/l. In 74% of cases, ARF occurred concomitantly or after admission to the ICU. Oligoanuria was present in 38%, whereas polyuria was observed in 17%. Fourteen ARF patients (33%) required dialytic support. Mortality rates were significantly different in ARF vs. non-ARF patients (88 vs. 60%, p < 0.05). Predictive factors for the development of ARF were liver failure (odds ratio (OR) 5.9), low serum albumin (OR 1.2) and APACHE II score (OR 1.1), whereas variables predictive of mortality were mechanical ventilation (OR 14.8), ARF (OR 5.8), liver failure (OR 3.7), and APACHE II score (OR 1.2). Conclusions: This study confirms that ARF in BMT patients admitted to the ICU is frequent, multifactorial, related to liver failure, and that its development has a negative impact on outcome.