In this Phase II, randomized double-bind study, the efficacy of Celecoxib in actinic keratosis (AK) patients will be evaluated. Eligibility criteria include female and male subjects over 18 years of age with multiple sites (at least two) of actinic keratosis identified by clinical examination and histologic confirmation of one lesion (Grade 1-3), no history of invasive cancer within five years, not requiring topical medications, and meeting SWOG performance status. Approximately 120 subjects will be randomized to Celecoxib vs. placebo. The endpoints of the study are the efficacy of Celecoxib on regression of AK when administered for one year compared to placebo and to determine the effect of Celecoxib on surrogate endpoint biomarkers of actinic keratosis and sun damaged skin.