Interferon-gamma (IFN-gamma), which is a member of cytokine family, has many physiological functions. In this study, we evaluated the effects of IFN-gamma on wound healing in a model of incised wound of rat skin. Twenty Wistar rats were divided into three groups, consisting of IFN-gamma local administration (n = 8), IFN-gamma systemic administration (n = 8) and normal saline control (n = 4). IFN-gamma was administered in doses of 2,000 u/rat, and then daily. Wound areas were measured everyday. At day 10, tissue from wounds was obtained, and it was evaluated for protein amount in granulation tissue and also subjected to morphometric analysis with hemotoxylin and eosin and collagen fibril stain. We found that IFN-gamma impaired wound healing after either systemic or local administration as compared with control, as evidenced by reduction of new collagen fibril deposition and delay of reepidermidalization. On days 7 and 10 after wounding, wound area in normal saline treated rats was much smaller than those in rats treated with IFN-gamma. These results indicated that the impairing effects of IFN-gamma on wound healing must be considered when it is used in clinic.