Chronic granulomatous disease (CGD) results from constitutional inactivating mutations in the CYBB, NCF1, CYBA or NCF2 genes that encode subunits of phagocyte NADPH oxidase. We report the findings of molecular analysis of 80 kindred. In 75 unrelated male and 5 female probands, CGD was suspected on the basis of clinical symptoms, and biological samples were referred to our laboratory between 2000 and 2007. Seventy seven patients were found to have mutations in CYBB, NCF1, CYBA or NCF2 (52 different mutations including 31 mutations not previously reported). CYBB was the most frequently mutated gene (58 males and 3 females, 76%). In autosomal recessive forms of the disease, mutations were found in NCF1 (11 patients), NCF2 (3 patients) and CYBA (2 patients). We observed that significantly fewer females were affected by autosomal recessive CGD than expected (2 females/14 males; p=0.002), suggesting that female patients with CGD may be under diagnosed.