An essential component of type 1 diabetes mellitus is autoaggression of the immune system against insulin-secreting pancreatic cells. It is thought that early destruction of the autoaggressive mechanism prior to the complete damage of beta cells should halt this process. In a 28-year-old male patient with a 4-week history of type 1 diabetes mellitus, three courses of plasmapheresis had been performed before cyclophosphamide, 2 g/m2 body surface area, was administered and hematopoietic cells were obtained. Six weeks after the diagnosis, 4 doses of cyclophosphamide 50 mg/kg body weight were again administered together with antithymocyte globulin, and autologous hematopoietic cells were transplanted. The procedure was associated with no significant side effects. Insulin requirement started to drop from the first course of plasmapheresis, and the patient has remained normoglycemic with no need of exogenous insulin or other hypoglycemic agents since the third week after the procedure, which has been 5 months until publication of this report. Independence from exogenous insulin is associated with the implemented therapy (a gradual decrease in insulin requirement has been observed after consecutive stages of the immunosuppressive treatment, with total discontinuation after bone marrow transplantation). The course of the disease and the type of treatment may suggest that such medical procedures could eliminate autoaggressive mechanism in diabetes and prevent further degeneration of insulin-producing cells, thus becoming a new therapeutic option for patients with type 1 diabetes mellitus.