Lichen planus (LP) is an idiopathic, chronic, inflammatory, autoimmune dermatological disorder characterized by keratinocytes apoptosis. The pathogenesis of LP appears multifactorial. chitinase-3-like protein1(CHI3L1) has been found to play a role in inflammation, proliferation and angiogenesis. The aim of the current study was to evaluate tissue CHI3L1 levels in skin biopsies of LP patients to investigate its role in LP pathogenesis. In 30 LP patients and 30 healthy controls, CHI3L1 level was estimated using Polymerase Chain Reaction (PCR) technique. The expression of CHI3L1 was significantly higher in tissue biopsies from LP lesions in comparison to normal control biopsies. Thus, CHI3L1 might participate in the pathogenesis of LP.