We report a 14-year-old boy who had successfully received allogeneic BMT for chronic granulomatous disease and 3 years later was treated with donor lymphocyte infusion (DLI, 3.3 x 10(8) cells/kg) at unstable mixed chimerism in association with reduced neutrophil function. Following DLI, the patient developed transient acute hepatic GVHD, which was confirmed by liver biopsy and was manageable with cyclosporin A and prednisolone. The patient eventually attained complete chimerism with improved neutrophil function. At the time of writing (2.5 years from the DLI), the patient is doing well, free from infectious episodes and chronic GVHD. Our experience suggests that DLI could be a safe and effective strategy for dissolution of unstable mixed chimerism in BMT recipients for inherited disorders.