Since the 1970s there has been an increase in the number of bone marrow and stem cell transplantations as well as a decrease in transplantation-associated fatalities due to improved transplantation techniques and supportive therapy. Annually nearly 50,000 transplantations are conducted worldwide with matched family grafts and matched or sometimes mismatched unrelated donor grafts. The number of long-term survivors is increasing and the late complications of this relatively aggressive therapy are now becoming apparent. This article is essentially concerned with the delayed complications of bone marrow and stem cell transplantations. Despite curing the malignant primary disease the total survival of transplantation patients is reduced. The main reasons are infection, organ dysfunction and therapy-associated secondary neoplasms. Among the high risk factors are total body irradiation, chronic graft versus host disease as well as treatment during childhood. Guidelines for the follow-up care of these long-term survivors were first published in 2006 and then updated in 2011.