Recent studies have shown clinical benefit resulting from recombinant interferon gamma (rIFN-gamma) therapy in patients affected by chronic granulomatous disease (CGD), which represents an important adjunct to conventional therapy. In order to evaluate the effect of interferon gamma therapy, we investigated clinical and haematological parameters in a child with X-linked CGD, McLeod phenotype (kell negative) and hyper-IgE, before and after 8 months of therapy. Our results show no significant effect of rIFN-gamma on the respiratory burst of peripheral polymorphonuclear leukocytes. This notwithstanding, we observed improved clinical and haematological conditions. These results support the view that interferon gamma may benefit these subjects by influencing oxygen-independent antimicrobial activity or other immunological parameters.