Between 1999 and 2005, 285 patients received new diagnoses of myelofibrosis with myeloid metaplasia (MMM) in Japan. Anemic symptoms were present in 162 patients, and hemoglobin (Hb) concentrations were <10 g/dL in 197 patients. Fifty-five MMM patients were treated with anabolic steroids, and their effect on anemia during MMM was evaluated in 39 patients. A "good" response was defined as an Hb increase of >or=1.5 g/dL, cessation of transfusion dependence, and an Hb concentration of >10 g/dL maintained for at least 8 weeks. A "minimum" response was defined as an Hb increase of >or=1.5 g/dL and transfusion independence for at least 8 weeks. Both good and minimum responses were considered "favorable." Favorable responses were achieved in 17 patients (44%, 8 good and 9 minimum responses). None of the pretreatment variables, such as the lack of transfusion dependence, a higher Hb concentration at the start of treatment, or the absence of cytogenetic abnormalities, were associated with a response to anabolic steroid therapy. Adverse events associated with anabolic steroid therapy were moderate and transient. Two patients required definitive withdrawal of treatment. Thus, anabolic steroids are well tolerated and effective for the treatment of anemia in a subset of MMM patients.