Agnogenic myeloid metaplasia (AMM) is a chronic myeloproliferative disorder in which patients with poor prognostic features, receiving conventional treatments, have a median survival of less than 3 years. In this retrospective multicenter study, we analyze the results and try to define the indications for allogeneic stem cell transplantation in AMM. From January 1979 to November 1997, 55 patients with a median age of 42 years were transplanted from HLA-matched related (n = 49) or alternative (n = 6) donors for AMM. A multivariate analysis was conducted to identify factors associated with posttransplant outcome. The median posttransplant follow-up was 36 months (range, 6 to 223). The 5-year probability of survival was 47% +/- 8% for the overall group, and 54% +/- 8% for patients receiving an unmanipulated HLA-matched related transplant. The 1-year probability of transplant-related mortality was 27% +/- 6%. Hemoglobin level =100 g/L and osteomyelosclerosis before transplant adversely affected the outcome. The probability of developing grade III-IV acute graft-versus-host disease (GVHD) was 33% +/- 8%. Sixteen of 45 patients developed extensive chronic GVHD. At last follow-up, 22 patients were in complete histohematologic remission. Treatment failure was observed in 13 cases. Age at transplant and karyotype were predictors of treatment failure. Allogeneic stem cell transplantation is an effective treatment leading to cure in a substantial number of patients with AMM. A better characterization of the variables affecting the posttransplant outcome should lead to a decreased transplant-related mortality and an improvement in these results.