The course of 260 adults with haematological malignancies admitted to a medical intensive care unit was studied to evaluate the value of life support techniques and to research predictive factors. The overall in the medical intensive care unit (MICU) and hospital mortality rates were respectively 43% (113 patients) and 57% (148 patients). Among survivors, 64% (49 patients) were still alive after 6 months and 44% (35 patients) after 1 year. Among 34 haemodialysed patients, the MICU mortality was 67% (23 patients) and among 111 mechanically ventilated patients 85% (94 patients). Prolonged mechanical ventilation, more than seven days, was performed in 11 of the 17 survivors and did not influence long term survival. No individual predictor of mortality was found comparing survivors and non-survivors. However, SAPS, intractable sepsis and failure of more than one organ system were significantly different in non-survivors (p less than 0.001). Among the 20 patients requiring both mechanical ventilation and haemodialysis, only two left the MICU and both died soon thereafter. We conclude that life support therapy should be initiated in patients with haematological disorders and that prolonged mechanical ventilation is compatible with long term survival. However, the combination of mechanical ventilation and haemodialysis is always associated with a poor prognosis and therefore the use of both techniques simultaneously for one patient is questionable.