OBJECTIVES: To evaluate the outcome of hematopoietic stem cell transplantation (HSCT) in a series of patients with inherited complete IFN-gamma receptor 1 (IFNgammaR1) deficiency. STUDY DESIGN: We report 8 patients who received altogether 11 HSCT from family donors, including 10 HLA-identical (5 siblings and 5 relatives) and 1 HLA-haplo-identical donors. Five grafts were T-cell depleted, and conditioning regimens varied in intensity. RESULTS: Four patients died within 8 months after HSCT. Two of these deaths were due to specific complications related to mycobacterial infection. There was no or very low (2%) donor cell engraftment in 2 survivors. Only 2 patients are in full remission of mycobacterial disease 5 years after HSCT. These are the only patients who received non-T-cell-depleted grafts from an HLA-identical sibling after a fully myeloablative conditioning regimen. CONCLUSIONS: HSCT can lead to prolonged remission of mycobacterial disease in children with complete IFNgammaR1 deficiency. However, optimal control of mycobacterial infection before HSCT and the use of a non-T-cell-depleted transplant from an HLA-identical sibling after a fully myeloablative conditioning regimen are recommended.