Abstract: Objective: To detect the level of Caspase-3 in the lesions of cutaneous squamous cell carcinoma and actinic keratosis. Methods：The level of Caspase-3 in 16 lesions of cutaneous squamous cell carcinoma，27 lesions of actinic keratosis and 24 normal skin was detected by immunohistochemistry method. Results：The positivity rate of Caspase-3 in the lesions of cutaneous squamous cell carcinoma, actinic keratosis and normal skin tissues was 37.50%, 51.85% and 79.17% respectively. The expression quantity of Caspase-3 in the lesions of cutaneous squamous cell carcinoma, actinic keratosis and normal skin was increased gradually. Conclusion：The down-regulated expression of Caspase-3 may be involved in the pathogenesis of cutaneous squamous cell carcinoma and actinic keratosis.

Key words: Caspase-3, cutaneous squamous cell carcinoma, actinic keratosis