Background: Lichen planus (LP) is an idiopathic, chronic, relapsing, inflammatory, autoimmune dermatological disease. The etiopathogenesis of LP is still unclear. Autophagy is a strictly regulated lysosomal degradation pathway that is crucial for maintaining intracellular homeostasis and normal development. The dysregulation of autophagy-associated genes was recognized to increase the susceptibility to multiple diseases, including inflammation, autoimmune disorders and cancer. Aims: Our study aimed to detect the expression of autophagy-related gene 9 b (ATG9B) in LP patients compared to normal control persons to investigate the possible role of autophagy in pathogenesis of this disease. Methods: This case–control study included 30 LP patients and 30 age-, gender-matched healthy controls. Four millimeters punch skin biopsies were obtained from LP lesions and from the controls and they were kept in lysis solution for the stability of the studied parameters and were kept frozen at –80°C till analysis of ATG9B using real-time polymerase chain reaction. Results : The level of ATG9B in lesional skin of LP was significantly decreased compared to normal control persons (P < 0.01); also, there was a non-significant relation between ATG9B level and age, sex, duration and family history among LP patients. Limitations: Limited number of patients included in our study (30 patients). Conclusion: Autophagy may play a role in the pathogenesis of cutaneous LP.