Abstract: The immunohistochemical staining showed the connexin 43 (Cx43) was strongly expressed (average gray value, AGV=230±5), distributed at junction area and intercalated disks of cardiocytes in normal rats,and much less expressed (AGV 193±4) (P<0.01) and distribution-disorganized in STZ-induced diabetic rats. This may be associated with the pathogenesis of diabetic myocardial lesions.