Treatment with photodynamic therapy followed by imiquimod 5% cream has been reported in patients with actinic keratoses, basal cell carcinoma and Bowen's disease, and treatment with imiquimod 5% cream followed by photodynamic therapy in patients with vulvar intraepithelial neoplasia. There are, however, no prior studies on the safety and/or efficacy of using topical imiquimod 3.75% in conjunction with photodynamic therapy in the treatment of actinic keratoses.