Objective：To investigate the protein expression of GATA-4 in the developing rat hearts. Methods：Embryolc hearts of normal rats were obtained on the 12 th, 15 th and 19 th day during embryonic period. The expression level of GATA-4 protein was accessed by Western blot and Immunohistochemistry, and the results were analyzed by the statistical method of One-way ANOVA. Results：GATA-4 was expressed in atrial ventricular myocardium,endocardium, endocardial cushion and the root of main artery, Ｔhe expression of GATA-4 in the heart was ｉｎｃｒｅａｓｉｎｇ ｏｂｖｉｏｕｓｌｙ ｏｎ １５ ｔｈ ｄａｙ ｉｎ ｅｍｂｒｙｏｎｉｃ ｐｅｒｉｏｄ, but it was slightly ｄｅｃｒｅａｓｉｎｇ ｏｎ １９ ｔｈ ｄａｙ． Conclusion：With the development of rat hearts, the protein expression of GATA-4 was dynamic. It was suggested that GATA-4 should play a crucial role in rat heart development.