The physicochemical properties of the optimized microemulsion and the permeating ability of oxyresveratrol in microemulsion were evaluated, and the efficacy of oxyresveratrol microemulsion in cutaneous herpes simplex virus type 1 (HSV-1) infection in mice was examined. The optimized microemulsion was composed of 10% w/w of isopropyl myristate, 35% w/w of Tween 80, 35% w/w of isopropyl alcohol, and 20% w/w of water. The mean particle diameter was 9.67 +/- 0.58 nm, and the solubility of oxyresveratrol in the microemulsion was 196.34 +/- 0.80 mg/ml. After accelerated and long-term stability testing, the microemulsion base and oxyresveratrol-loaded microemulsion were stable. The cumulative amount of oxyresveratrol permeating through shed snake skin from microemulsion at 6 h was 93.04 times compared to that of oxyresveratrol from Vaseline, determined at 20% w/w concentration. In cutaneous HSV-1 infection in mice, oxyresveratrol microemulsion at 20%, 25%, and 30% w/w, topically applied five times daily for 7 days after infection, was significantly effective in delaying the development of skin lesions and protecting from death (p<0.05) compared with the untreated control. Oxyresveratrol microemulsion at 25% and 30% w/w was significantly more effective than that of 30% w/w of oxyresveratrol in Vaseline (p<0.05) and was as effective as 5% w/w of acyclovir cream, topically applied five times daily (p>0.05). These results demonstrated that topical oxyresveratrol microemulsion at 20-30% w/w was suitable for cutaneous HSV-1 mouse infection.