Free radicals play important roles in the mechanisms underlying lichen planus (LP). Uric acid (UA) is an important anti-oxidant in plasma. Prolactin (PRL) is an immunomodulatory hormone that may promote LP, as has been documented in other autoimmune disorders, such as systemic lupus erythematosus, rheumatoid arthritis, and psoriasis. PRL has multiple immune-stimulatory effects and promotes the development of such autoimmune disorders. Prolactin and uric acid may serve as biomarkers of disease activity in lichen planus. The aim of the present study was to evaluate the roles of depression, stress, and anxiety in LP, as well as serum levels of UA and PRL as potential biomarkers of disease activity and compare these findings with those of the control group. Thirty-nine patients clinically diagnosed with oral LP (study group) and 39 age- and sex-matched controls (control group) were selected in this study. Serum UA and PRL levels were measured. The Depression Anxiety Stress Scale-21 was used for psychometric evaluation of LP patients and controls. Serum UA level was found to be significantly higher in the control group as well as during the remission phase of disease in the study. There was no significant difference in serum PRL levels between cases and controls. Depression and stress scores were higher in the study group.