Introduction: Oral Lichen Planus (OLP) is considered a T cell mediated disease with unknown etiology. T helper cells appear to play an important role in the pathogenesis of OLP.Interleukin-17 (IL-17) is the signature cytokine of T helper (Th) cells. Recent studies suggested that IL-17 may be involved in the pathogenesis of OLPand homeostasis of tissues beyond the immune system.Interleukin-17 receptor (IL-17R) expression is working in disparate tissuessuch as articular cartilage, bone, meniscus, brain, hematopoietic tissue, kidney, lung, skin and intestine. Aim of the study: This study evaluated the possible correlation between serum and tissue levels of IL-17 as well as the expression of its tissue receptor in order to detect their possible role in the etio-pathogenesis of OLP. Subjects and methods: 20 patients with OLP and 10 healthy volunteers were recruited. Serum and tissue IL-17 levels were assessed by using an Enzyme Linked Immune-Sorbent Assay (ELISA), whileIL-17R gene expression was detected by quantitative real time polymerase chain reaction (qRT-PCR). Results : Results showed that the mean serum and tissue levels of IL-17 as well as mean tissue level of IL-17R in OLP were significantly higher compared to the controls (P value < 0.001),and there was a statistically significant positive (direct) correlation between serum IL-17 andboth tissue level of IL-17 and its tissue receptor. Discussion : This study demonstrated the increased expression of serum and tissue level of IL-17 and IL-17 tissue receptor in OLP patients, suggesting that IL-17 and its receptor in affected tissues may be associated with the pathogenesis of OLP and that IL-17 may be considered an important diagnostic pro-inflammatory cytokine in OLP. Conclusions and recommendations: Further studies are required to investigate the immune-pathologic mechanisms and therapeutic target of IL-17 in OLP.