The aim of the present controlled study was to investigate a possible relationship between contact allergies to potential allergens and oral lichen lesions. Eighty-three patients with oral lichen lesions (OLL) and control groups of age- and gender-matched dermatitis patients (DP, n = 83) and patch-tested dermatitis patients randomly selected from files (PSFF, n = 319) were included in the study. OLL and DP groups were patch-tested epicutaneously and examined intraorally. The frequencies of contact allergy to mercury and carvone were statistically higher in the OLL group than in the DP group. Surfaces of amalgam and composite restorations were statistically more frequent in the OLL group compared to the DP group. Contact allergy to nickel and colophony, the latter with a statistically significant difference, was more common in the DP group. The numerical difference found for nickel allergy was, however, not significant comparing the OLL and PSFF groups. Contact allergy to mercury was overrepresented in patients with OLL and has been reported in previous studies, but the present finding of an overrepresentation of contact allergy to carvone in patients with oral lichen lesions has not been reported previously. Carvone, in addition to mercury and gold, as previously suggested, can be one of the causative or maintenant factors for oral lichen lesions. Carvone-hypersensitive patients with oral lichen lesions should therefore avoid carvone-containing products for oral use.