A 36-year-old Japanese man was hospitalized with coughing and exertional dyspnea (NYHA class I). He was diagnosed as having congestive heart failure, and was treated with diuretics and a beta-adrenergic blocking agent. He responded well to the treatment and his symptoms completely disappeared within a few days. Based on his clinical, laboratory, and molecular genetic findings, he was diagnosed as having X-linked dilated cardiomyopathy (XLDCM). He was found to have a large deletion in the dystrophin gene, involving exons 45-55. This is the first report on a Japanese XLDCM patient with a mutation in the central hot-spot region of this gene.