Many articles pertaining to quality of life (QOL) following stem cell transplantation have been published in the US and western Europe. However, since the actions of health insurance systems and overall cultural aspects are strongly associated with QOL, investigations into QOL should be carried out within all countries. Therefore, we have investigated the QOL of adult patients following stem cell transplantation at 31 hospitals in Japan. The survivors, who were surveyed by mail questionnaire, were 20 years or older at the time of this study. The underlying diseases were acute lymphoblastic leukemia, acute myelogenous leukemia, chronic myelogenous leukemia, non-Hodgkin's lymphoma, Hodgkin's disease, myelodysplastic syndrome, and multiple myeloma. Median age at the time of the study was 36 years, and median interval after transplantation was 35.3 months. Of 383 patients surveyed, 282 (73.6%) responded to the questionnaire. One hundred and ninety-two patients were treated with an allogeneic-related transplantation, 52 with allogeneic-unrelated, and 38 with an autologous transplantation. Our data revealed that the length of time since transplantation and the diagnosis of chronic GVHD were associated with QOL. When unrelated and related transplantation recipients were compared, ratings on relief from pain, stability in weight, and confidence in dealing with daily life were lower among unrelated transplantation patients.