It is of large importance to identify abnormalities and pathologies of the oral mucosa. In this perspective, the use of non-invasive optical techniques such as OCT provides the opportunity to complement common diagnostics. Especially in cases of recurrent or multiple lesions, OCT diagnosing promises a thorough and, if necessary, repeated assessment of the oral mucosa without the drawbacks of invasive procedures. For this reason, the number of studies on in vivo OCT examination of suspicious oral mucosal lesions is continually increasing. At the same time, there are only a few studies focusing on imaging pathologically altered oral mucosa. Against this background, the aim of this work was to characterize pathological oral mucosa with the clinical diagnosis of OLP in various areas of the oral cavity and additionally diagnose it using OCT imaging. An endoscopic in vivo OCT examination, in addition to conventional diagnostics, was conducted on 22 adult patients. The examination involved three measurement points, but only two were included for further analysis: the pathological center and the transition to healthy mucosa. Subsequently, image analysis was performed based on qualitative criteria to assess the oral mucosa. The parameters for examining OCT scans included EP thickness, delineation/visibility of the basement membrane, EP reflectivity, LP reflectivity and visible vascular network in the lamina propria. For classified OLP in general, the structural changes in the oral mucosa were compared to the normal state and the parameters of healthy oral mucosa served as a basis for determining the altered morphology in OCT, depending on the clinical classification of OLP. This made it possible to derive OLP-specific features in OCT. The goal of this dissertation was also to relate in vivo depth-resolution cross-sectional image information from OCT to the clinical diagnosis and compare certain parameters of different OLP forms. The transition from a normal to a pathological finding is sometimes clinically challenging to define, as is the appropriate area for a biopsy in an extensive and widespread oral lesion or alteration. In the future, non-invasive optical biopsy could be helpful in this regard. In this case series, as a first step, OCT cross-sectional images of central and peripheral areas of various types and subtypes of OLP were non-invasively captured and correlated with visual clinical findings and, if available, with histopathology. By identifying and describing OLP-specific features in OCT cross-sections for different forms of OLP, we establish a foundation for the non-invasive differentiation of suspicious dysplastic lesions from OLP and other pathology was established. This may improve biopsy sampling in the future and ensure reliable histopathological assessment. The next step is to further investigate the proposed OCT technology in clinical studies with a larger number of cases, obtaining robust data on the sensitivity and specificity of OCT for distinguishing various forms of OLP, as well as for distinguishing dysplastic changes and squamous cell carcinomas.