RESUMEN
<p><b>AIM</b>To observed the expression of estrogen receptor (ER alpha and ER beta) in the heart of Gekko swinhonis.</p><p><b>METHODS</b>The immunohistochemical technique for the estrogen receptor was used.</p><p><b>RESULTS</b>The positive ER alpha and beta cells existed in cardiac myocytes and fibroblasts of the atria and the ventricles of Gekko swinhonis and had no sexual difference. The difference of ER alpha between the atria (11.56 +/- 1.67) and ventricles (6.68 +/- 1.88) was observed in both sexes (P < 0.01).</p><p><b>CONCLUSION</b>The atria are probably the main target tissue of estrogen through ER alpha pathway while some functions of whole heart will be regulated by estrogen through ER beta pathway. The sexual differences aren' t related to the content of ER. It may be involved in the state of activity and function of ER under the physiological conditions.</p>