Background: Actinic cheilitis is a common precancerous disorder of the lower lip caused by ultraviolet radiation. Photodynamic therapy (PDT) is a potential treatment for actinic cheilitis, however controlled clinical trials regarding this treatment are needed.Objective: To evaluate the safety and efficacy of PDT with blue light and topical δ-aminolevulinic acid (Levulan®) in the treatment of actinic cheilitis.Methods: We conducted a single center, investigator-initiated, nonrandomized, open-label, proof of concept study of PDT with blue light for the treatment of actinic cheilitis. We enrolled 24 subjects, 20 meeting inclusion and exclusion criteria. One subject withdrew from the study prior to treatment. The study consisted of a screening visit, one to three scheduled treatments, and two follow-up visits. The primary outcome was clinical improvement in actinic cheilitis from baseline, estimated as no (0%), mild (25%), moderate (50%), marked (75%), or excellent improvement (100%). Post-treatment assessment of swelling, erythema, flaking/scaling, crusting, vesiculation/pustulation, and erosion/ulceration was also recorded. Subjects completed the Dermatological Life Quality Index questionnaire, subject global assessment of improvement, and pain assessment at each visit.Results: 65% of subjects achieved clinical improvement of 75% or greater and 20% achieved 100% improvement by the end of the study. Treatments were well tolerated with minimal discomfort. Subjects experienced transient mild adverse effects.Conclusion: Overall, our study supports using PDT for the treatment of actinic cheilitis.