A 23-year-old woman with heterozygous Fabry's disease who had acroparesthesia was admitted to hospital for precise examination of the disease before childbearing. She had no cardiac-related symptoms and no abnormality on physical examination. The alpha-galactosidase A activity in her leukocytes was present, but lower than normal. However, the endomyocardial biopsy showed specific changes for Fabry's disease. As Fabry's disease is a rare X-linked recessive inborn error of glycosphingolipid metabolism, heterozygous females are usually asymptomatic, but rarely can be affected as severely as hemizygous males. This is an isolated case of heterozygous Fabry's disease in a female in whom cardiac involvement was detected by endomyocardial biopsy, although she had no cardiac abnormality on physiological examinations. In conclusion, endomyocardial biopsy is useful for evaluation of the cardiac involvement of Fabry's disease even in an asymptomatic case.