Immunosuppression with chemotherapy followed by autologous haematopoietic stem cell transplantation has proven to be an effective long-term treatment for younger patients with relapsing-remitting multiple sclerosis and clinical as well as radiological evidence of high disease activity. The conditioning regimen can be of either high, intermediate or low intensity. Due to the safety profile and favourable efficacy measures, the low intensity regimen cyclophosphamide + anti-thymocyte globulin is currently used in Denmark as standard regimen.