A 46-year-old woman was given a diagnosis of primary myelofibrosis (PMF) in 1996. Because of the progression of anemia and splenomegaly, she was scheduled for allogeneic bone marrow transplantation (BMT) from an HLA-matched sibling donor in April 1998. Cyclophosphamide and busulfan were used as the conditioning regimen. Before BMT, the patient was treated with hydroxycarbamide, which did not resolve splenomegaly. She then underwent a splenectomy, which was followed by massive portal vein thrombosis without any significant clinical outcome. After BMT, the patient obtained rapid hematologic engraftment. Moreover, the alleviation of marrow fibrosis was confirmed 4 months after BMT. We concluded that allogenic BMT can cure patients with PMF, but that the issue of splenectomy and the indications for BMT need to be evaluated further.