This article is intended to study histopathological and immunohistochemical response after autogenous full-thickenss skin graft in rat. 12 male Sprague-Dawley rats were used as the experimental animals. A $1Cm{ imes}1Cm$ skin(0.7mm diameter) was taken on the right inguinal area of the rat. Another full-thickeness skin graft($1Cm{ imes}1Cm$) was taken from the left inguinal area of the rat. And it was transplanted to the right inguinal area of the rat. The left side wound was closed directly. Light microscopic observation was made at the postoperative $1^{circ}3^{circ}8^{circ}16$ day, after the hematoxylin - Eosin staining of the 4u-thick paraffin embedded specimens and the immunoshitochemical staining of the 10u-thick frozen specimens with mouse anti-rat monoclone antibodies and ABC staining kit. The results were as follows. 1. Electromicroscopic studies revealed interstitial tissue bleeding of transplanted autogenous skin. The response was severe in the 1 day group after operation, moederate in 3 day group, mild in 8 day group, and almost resovled in the 16 days group. 2. Electromicrospic studied also revealed a mild monocyte response in the 3 day and 8 day group. A histiocytic infiltrate was observed. There was a mild response in the 3 day group and moderate response in the 8 day group. 3. Immunohistochmically studies revealed a few pan T cells in the 1 day group, mild appearance of pen T cells and cytotoxic T cells in the 3 day group, a moderate infiltrate of pan T cells and helper T cells in the 8 day group, and total resolution of pan T cells in the 16 day group. 4. According to these finding, a strong inflammatory response was observed around transplanted autogenous skin in the 3 & 8 day groups. In the 16 day group this response had resolved histopathologically and immunohistologically.