Abstract The prognosis of allogeneic stem cell transplant recipients admitted to the intensive care unit (ICU) has improved over the last decades. However, data focusing on patients treated in the ICU during the peri-transplant period are scarce. We therefore conducted an analysis comprising 70 patients who had allogeneic stem cell transplantation at the University Hospital Cologne between 2014 and 2020 and were admitted to the ICU between the initiation of conditioning therapy and day 30 after transplantation. The median age was 59 years (range: 18 − 72 years). 50% of patients were female. Sepsis was the most common cause for ICU admission (49%). Mechanical ventilation (MV) was required in 56% of patients, 27% had renal replacement therapy (RRT), and 64% needed vasopressors. The ICU, hospital, 90-day, and 1-year survival rates were 48.6%, 38.6%, 35.7%, and 16.2%, respectively. MV and/or RRT during the ICU stay were associated with an impaired survival (p < 0.0001). The same was true for the use of vasopressors (p < 0.0001). In contrast, baseline characteristics did not impact the outcome. Cardiopulmonary resuscitation (CPR) was performed in 17% of patients. None of the patients undergoing CPR was alive at 1 year. Among patients who died after discharge from the ICU (n = 23), sepsis and other infectious complications represented the major causes of death (48%). Taken together, the present analysis indicates unfavorable outcomes for allogeneic stem cell transplant recipients admitted to the ICU during the peri-transplant period. The data may help to make informed decisions with patients and their families.