Background: The concept of contact allergy aggravating or inducing oral lichenoid mucositis diagnosed as oral lichen planus (OLP) is well recognized but somewhat controversial. Objective: We sought to identify clinically relevant contact allergens that may be important in the management of patients with OLP. Methods: We retrospectively reviewed patients with OLP who had patch tests performed at Mayo Clinic Rochester and Mayo Clinic Scottsdale from 1994 to 1997 and 1988 to 1997, respectively. Results: Patch tests were performed on 46 patients with a clinical and histopathologic diagnosis of OLP. Of these, 25 (54%) had positive patch test results. Eighteen (72%) of the patients with positive results had clinically relevant reactions. Of the patients with positive metal reactions, 5 had improvement after removal of the metal prosthesis or restoration. Six others noted that their most troublesome areas were adjacent to metal dental restorations. Six patients with reactions to flavorings and one patient with an acrylate dental retainer sensitivity had improvement after avoiding these allergens. Conclusion: Our findings support the concept that contact allergy to metals, flavorings, and plastics can be important in the pathogenesis and management of patients with oral lichenoid mucositis diagnosed as OLP. (J Am Acad Dermatol 2000;42:177-82.)