Currently, non-invasive methods for studying the structure of biotissues are being introduced into clinical practice, which in some cases could constitute an alternative to biopsy. Optical coherence tomography (OCT) is a high-resolution (10—20 μm) method for visualizing the structure of biotissues, approaching histological examination in terms of information. Aim: To study the possibilities of using 3D OCT in diagnosis of skin neoplasms. Material and methods. Non-invasive OCT study was conducted in 20 patients with various skin neoplasms in the clinic of Federal State Budgetary Educational Institution of Higher Education Privolzhsky Research Medical University of the Ministry of Health of Russia. In our study we used an optical coherent tomograph for non-invasive study of the internal structure of human superficial tissues OKT-1300-E (high-speed modification; 92,000 A-scans in 1 s) equipped with a specialized probe for studying external biological tissues with 3D modeling of optical «sections». Results. Use of 3D models of OCT images contributed to accurate visualization of the neoplasm and determination of its boundaries; it also made it possible to receive an arbitrary number of 2D «sections» of various planes of the object with the most typical manifestations. An analysis of a series of targeted 2D images within the neoplasm and its borders in three cases allowed us to register typical OCT signs of basal cell carcinoma (BCC), in two cases — melanoma, in three cases — dermatofibroma, in three cases — actinic keratosis, in three cases — common warts, in three cases — molluscum contagiosum, in two cases — seborrheic keratoma, which in combination with clinical data in all cases ensured the correct diagnosis and the selection of the optimal diagnostic and therapeutic tactics. BCC diagnosis was confirmed using punch biopsy; melanoma was confirmed histologically after radical excision. In the case of porokeratosis plantaris palmaris, it was diagnosed using 3D OCT data, contrary to the initial clinical diagnosis of plantar warts.