Agnogenic myeloid metaplasia is a rare indication for allogeneic bone marrow transplantation (BMT). We have retrospectively studied 12 patients allografted for this disease within the French BMT group. Prior to BMT, the mean age was 40 years (range 14-49). Diagnosis was based on the Polycythaemia Vera Study Group criteria. Before BMT, 10 patients had been splenectomized, eight required transfusions, and four had received at least two lines of chemotherapy. Cyclophosphamide and total body irradiation was the main conditioning regimen used (n=8). The donor was an HLA-identical sibling except in one case where there was one HLA-DR mismatch. Acute graft-versus-host disease (GVHD) prophylaxis consisted of methotrexate and cyclosporine A. 11 patients engrafted with median times to achieve absolute neutrophil count > 0.5 x 10(9)/l and platelet count > 50 x 10(9)/l of 17 (range 12-44) and 29 (range 12-196) days respectively. One primary graft failure occurred. 10 patients developed grade II-IV acute GVHD, four developed extensive chronic GVHD. One patient relapsed 16 months post-BMT and was untreated and well 14 months later. Three patients died from the BMT procedure. In May 1996 the median follow-up was 25 months and the 4-year overall and event-free survivals were 71% and 59%, respectively. Thus, we conclude that extensive myelofibrosis is not associated with delayed engraftment, and that HLA-identical sibling allogeneic BMT can be considered in a small proportion of patients with agnogenic myeloid metaplasia.