Various studies have shown that chitosan is effective in promoting wound healing. In this study, we aimed to develop an effective chitosan gel formulation containing epidermal growth factor (EGF), and to determine the effect on healing of second-degree burn wounds in rats. Ten micrograms per millilitre EGF in 2% chitosan gel was prepared. In an in vitro study to investigate release of EGF from the formulations, the release rate was 97.3% after 24 h. In in vivo studies, animals were divided into six groups as follows: silver sulfadiazine [Silverdin(R) cream (SIL)], chitosan gel with and without EGF (EJ, J), EGF solution (ES) and untreated control groups [unburned (S) and untreated (Y) rats] applied groups, respectively. A uniform deep second-degree burn of the backskin was performed with water heated to 94 +/- 1 degrees C during a 15-s exposure. The EGF formulations were repeatedly applied on the burned areas with a dose of 0.160 mu g/cm(2) for 14 days (one application per day). Healing of the wounds was evaluated immunohistochemically, histochemically and histologically on the tissue samples. When the results were evaluated immunohistochemically, there were significant increases in cell proliferation observed in the EGF containing gel applied group (p<0.001). The histochemical results showed that the epithelization rate in the EJ group was the highest compared to the ES group results (p<0.001). The histological results indicated and supported these findings. It can be concluded that a better and faster epithelization was observed in the EJ group compared to the other groups. (C) 2005 Elsevier Ltd and ISBI. All rights reserved.