Introduction. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is often complicated by life-threatening conditions.Aim — an analysis of the life-threatening complications in recipients of allogeneic hematopoietic stem cells (allo-HSCs)Main findings. From 10 to 50 % of allo-HSC recipients need to be admitted to the intensive care unit (ICU) due to the development of life-threatening complications. The reasons for ICU admission are acute respiratory failure, sepsis, graft-versus-host disease, veno-occlusive disease, thrombotic microangiopathy, cytokine release syndrome, engraftment syndrome, etc. Conditioning regimen, donor type, stem cell source, underlying disease state and patient comorbidity are the risk factors associated with development of life-threatening conditions. The main prognostic factors of unfavorable ICU outcomes in allo-HSC recipients are the severity of multiple organ dysfunction and the need for organ support.