Introduction: Lichen planus is an inflammatory disease of skin andoral mucosa. Evidence has accumulated that cytotoxic CD8+ve Tlymphocytes recognize an antigen on lesional keratinocytes and lysethem. Many authors considered Human herpes virus-7 (HHV-7) as apossible antigen for inducing cytotoxic immune response in lichenplanus. Studies suggested that type I interferons could play animportant role in cytotoxic inflammation in lichen planus. In humans,TLR9 is mainly expressed in plasmacytoid dendritic cells (pDCs).Activation of` pDCs through TLR receptors links the innate immunityto the adaptive one, leading to increased secretion of` IFN-α. Aim of the study: To evaluate tissue expression of TLR9 andHHV-7 mRNA in skin lesions of LP patients and to investigatewhether a relation exists between them, in an attempt to shed somelight on the role of innate immunity against HHV-7 exerted throughTLR9 in the pathogenesis of lichen planus. Patients and methods: the study included 30 skin biopsies fromlichen planus patients and 30 control biopsies. Both TLR9&HHV7-mRNA was detected by RT-PCR (Reverse-transcription polymerasechain reaction) technique. Results: Our analysis revealed significantly higher level of TLR9protein in all the lichen planus skin biopsies compared to controlbiopsies. The expression was significantly higher in HHV7 +vepatients than HHV7-ve patients. Conclusion: We concluded that HHV7 may induce lichen planus andTLR9 may play a role in the pathogenesis of LP.