Complete interferon-gamma receptor 1 (IFNgammaR1) deficiency is a primary immunodeficiency disease characterized by high susceptibility to recurrent, severe mycobacterial and other intracellular infections. We here report the first successful treatment of the disorder by bone marrow transplantation (BMT). The 8-year-old girl had suffered from recurrent mycobacterial infections in the past and had developed liver cirrhosis with portal hypertension. For conditioning, fractionated total body irradiation (TBI) was used in combination with cyclophosphamide and antithymocyte globulin (ATG). The patient received red cell-depleted bone marrow from her HLA-identical sister. The transplantation course was uneventful and 4 years later, the child remains in excellent clinical condition and free of mycobacterial infections. She has stable mixed lymphohematopoietic chimerism after repeat T-cell transfusions. Liver disease has not further deteriorated. This experience shows that correction of IFNgammaR1 deficiency is possible by BMT and complications of the disease can be controlled.