Although the disease was described over 100 years ago, the etiology of lichen planus still remains a mystery involving a possible interaction between genetic, environmental and life style factors. It is still unclear whether OLP represents a single disease or manifestation of several closely related conditions. The importance of this disease related to its degree of frequency of occurrence and its occasional painful nature. Although psychological disorder is commonly considered a factor in development and progression of OLP, this widely held assumption has not been substantiated. Studies using instruments to assess the mental status of these patients have resulted in conflicting results.