Background: Oral lichen planus (OLP) is a mucosal varient of lichen planus which tends to affect women more than men with a typically more chronic course and potential for significient morbidity. Aim of the work: The aim of the work was to study the effect of intra lesional injection of PRP in the treatment of OLP. Patients and methods: This therapeutic trial study included 18 patients with OLP collected from the out patient clinic of Dermatology, Venereology and Andrology Department, each of them had 5 sessions of intralesional PRP injection 2 weeks interval in between. Results: All of our patients were greatly improved after PRP sessions. This improvement was evaluated using REU scoring, and photographic assessment. Fortunately, almost all of our patients had no side effects to mention after PRP injection, nor any recurrence within 3 months after completing their sessions. Conclusion: PRP injection is an effective method in treatment of OLP.