Psychological factors may be associated with the outcome of cancer treatment, including bone marrow transplantation (BMT). However, studies on the issue have provided controversial results. In the present study, effects of mood status on the outcome was studied through a follow-up period of 1-3 years as well as in shorter periods (3 and 8 months) post-BMT in 72 Japanese patients with leukemia. Psychological status was evaluated 2 weeks before BMT using Profile of Mood States (POMS). The most major factor abstracted from the POMS subscales (Factor 1, mainly comprising anxiety, depression, anger, fatigue and confusion) was associated with disease-free survival rate at 3 months post-BMT. However, the factor most significantly associated with the outcome was gender. Females had better outcome than males through the period of 1-3 years as well as at 8 months post-BMT. When analyzed by gender, Factor 1 was associated with poor prognosis at 3 and 8 months in males. In females, however, Factor 1 was not significantly associated with the prognosis. The present results suggest an association between mood status pre-BMT and prognosis post-BMT in a gender-specific manner.