Abstract: Objective To observe the effect of intense pulsed light (IPL) on heat shock protein 70 (HSP70) expression in skin and elucidate the biological mechanisms of photorejuvenation. Methods The skin of 15 SD rats was exposed to IPL in 3 regions at the energy density of 34 J/cm² in triple pulses with the duration of 4, 5 and 6 ms, respectively, and pulse delays of 20 and 25 ms. On days 1, 3, 5, 7, 15 and 30 after treatment, specimens of the treated and untreated skin were taken, respectively, for determination of HSP70 expression by immunohistochemistry. Results In treated regions, positive immunohistochemical staining was observed on day 1 in the epidermal keratinocytes, sebaceous gland cells and endothelial cells. The staining reached the highest intensity on day 7, gradually weakened on day 15, and disappeared on day 30. In the untreated areas, the cells were negative for immunohistochemical staining. Conclusion Skin HSP70 expression can be enhanced by IPL, suggesting the role of HSP70 in photorejuvenation.