We evaluated the outcomes of allogeneic hematopoietic cell transplantation (HCT) in 43 patients with chronic myelomonocytic leukemia. Patients were classified according to the French-American-British and World Health Organization classifications, as well as the International Prognostic Scoring System and the M.D. Anderson prognostic score. Comorbidity scores were assessed by using an HCT-specific comorbidity index. Patients were aged 1 to 66 years (median, 48 years). Twenty-one patients received transplants from related donors (18 HLA-identical siblings and 3 HLA-nonidentical family members), and 22 received transplants from unrelated donors (18 HLA matched and 4 HLA nonidentical). Several busulfan or total body irradiation-based conditioning regimens were used. Sustained engraftment was achieved in 41 patients. Eighteen are alive at 1.9 to 14.1 years, for an estimated relapse-free survival of 41% at 4 years. Ten patients have relapsed, thus leading to a cumulative incidence of 23% at 4 years. Risk category by International Prognostic Scoring System, World Health Organization, M.D. Anderson prognostic score, or proliferative/dysplastic status had no statistically significant association with outcomes. However, patients with higher comorbidity scores had worse overall survival than patients with lower scores (P = .01). There was a trend for a higher relapse incidence among patients at higher risk by the M.D. Anderson prognostic score. The data suggest that patients with few or no comorbidities and those who undergo transplantation earlier in the disease course have the highest probability of successful outcome after allogeneic HCT.