RESUMEN
<p><b>OBJECTIVE</b>To observe the effect of an external film of hyaluronic acid (HA) on the rats wound healing.</p><p><b>METHODS</b>Forty-eight SD rats were randomly separated into eight groups of 6 rats each. Bilateral dorsal cuts were performed on each rat, left wound was used as the experiment with HA external film and right wound was used as the control only with normal saline. The process of healing was observed histologically following 1st, 3rd, 5th, 7th, 9th, 14th, 21st, and 28th days postoperatively.</p><p><b>RESULTS</b>Inflammation was lighter and epidermal healing was faster in the experimental group than those in the control. The fibroblasts degenerated and the collagen fiber changed to slim and loose bunches in the experimental group.</p><p><b>CONCLUSION</b>The results indicated that HA external film could have powerful infiltrating activity at the early stage of wound healing, it could accelerate the healing of epidermis and delay the formation of keratinization layer.</p>