Cystic fibrosis (CF) is an inheritable disorder characterized by defective epithelial chloride transport and progressive lung disease, caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. The subject of this study was an 8-year old Japanese boy, who developed typical CF symptoms including meconium ileus, pancreatic insufficiency, an elevated sweat chloride concentration and pulmonary disease. Analysis of the CFTR gene of this patient revealed compound heterozygous mutations in exon 11 (1742 delAC) and intron 9 (1525-18 GtoA) of the CFTR gene.