In the recent years, a better selection of patients and early management of organ dysfunction allowed an improved survival of critically ill hematological patients. However allogeneic bone marrow transplantation (BMT) recipients admitted to the ICU with severe organ dysfunction still have poor survival rates. We performed a large retrospective multicenter study to analyse the features and short-term and long-term outcomes of allogeneic BMT recipients admitted to the ICU. Between 1997 and 2003, 220 allogeneic BMT recipients were referred to 3 ICUs. Patients were classified in three groups, on the basis of time since BMT : group 1 (< Day 30) n= 73, group 2 (Day 31 to day 100) n= 59, group 3 (> day 100) n=88. The ICU overall mortality rate was 51% (112/220), 56% (41/73) in the group 1, 54% (32/59) in the group 2 and 44% (39/88) in the group 3. Twenty percent of patients (45/220) were alive at 6 months after ICU admission and 14% (31/220) were alive one year after. None of the pre-admission characteristics (age, underlying disease and disease status at the time of transplantation, type of transplant) was associated with prognosis in the ICU. Mortality rate was highly correlated with the number of organ dysfunctions as measured by the Logistic Organ Dysfunction (LOD) score at admission (LOD score < 5 : 30%, LOD score = 6 to 10 : 56%, LOD score ≥ 11 : 96%). Of the 119 patients who required invasive mechanical ventilation, 83% died (98/118). Among the ventilated survivors, 11% (13/118) and 6% (7 /118) remained alive at 6 months and one year respectively. In a multivariate logistic regression analysis, the requirement of invasive mechanical ventilation (OR 19.5, CI 95% 8.8–45.3, p<0.0001) and hepatic dysfunction with elevation of serum bilirubin >68 μmol/L (OR 4.7, CI 95% 1.9–11.4, p=0.0006) were independently associated with mortality. Although the requirement of invasive mechanical ventilation remains desperately associated with a high mortality rate, some allogeneic BMT recipients may have a good long-term outcome. Assessment of other organ failures, and particularly hepatic dysfunction, may lead to early identification of patients with very high probability of death.