Immunohistochemical and biochemical analyses of several tissues were performed in two unusual cases of Fabry's disease which showed accumulation of globotriaosylceramide (Gal alpha 1-4Gal beta 1-4 Glc-Cer, Gb3Cer) only in the hearts, but no clinical signs of the disease. Immunohistochemical study revealed that the hearts from our cases (cases no. 1 and 2) contained large amounts of anti-Gb3Cer antibody-positive granules in cytoplasms as in typical Fabry's disease. The contents of accumulated Gb3Cer in the hearts from case no. 1, case no. 2, and a typical Fabry's disease case were approximately 100, 340, and 100 times higher than those from normal controls, respectively. While typical Fabry's diseased kidney and liver contained approximately 40 and 50 times higher amounts of Gb3Cer than did controls, no accumulation of Gb3Cer was observed in kidney and liver of our cases. The only exception was a slight increase of Gb3Cer in kidney of case no. 2 (about two times higher than controls), in which epithelial cells of the glomeruli but not of other types of cells were positively stained by anti-Gb3Cer antibody. Case no. 1 kidney and liver were not stained by the antibody. The glomerular endothelium and epithelium, tubular epithelium, smooth muscle of renal arteries, and several hepatocytes were Gb3Cer-positive in the typical Fabry's disease case. The involvements of our cases differed distinctly from the typical Fabry's disease case.