Acquired, idiosyncratic aplastic anaemia (AA) is a rare but potentially fatal haematological disorder. Severe AA constitutes an acute medical emergency, and supportive therapy is needed to prevent overwhelming sepsis or a life threatening haemorrhage. Specific therapy for the disease includes the choice between allogeneic stem cell transplantation (SCT) from an HLA-identical sibling or immunosuppressive therapy with anti-thymocyte globulin (ATG) and cyclosporin A (CSA). Long-term cure rates of 75-90% are now achieved following HLA (human leukocyte antigen) identical sibling bone marrow transplant. The use of donors other than HLA-id siblings for transplantation in AA remains experimental. Transplantation offers the patient a chance of cure, whilst treatment with immunosuppressive therapy carries a long-term risk of relapse and clonal transformation. The haemopoietic growth factors, apart from granulocyte colony stimulating factor (G-CSF), have been shown to be potentially toxic when given to patients with AA. A short course of G-CSF may be useful to help treat severe infection, but its longer-term use with ATG and CSA remains controversial. Results from immunosuppressive treatment continue to improve with time, as a result of the additional use of CSA with ATG, the use of repeat courses of ATG for non-responders and improvements in the supportive care of patients.