INTRODUCTION: Molecular oncology is currently undergoing a fairly rapid development due to the emergence of new technologies and modernization of already known methods. These technologies allow not only to update and clarify the understanding of the molecular genetic nature of tumors, but also to develop new directions for the therapy and the course of cancer diseases. The prerequisite for this scientific direction was the decoding of the human genome, as a result of which most human genes have been identified and mapped by now. Microarray technology has been since the late 1980s and has been rapidly developing since then. In a short time, biological microarrays have evolved into an independent field of analysis, including both the study of fundamental problems of molecular biology and molecular evolution, and practical applications in medicine, pharmacology, forensic expertise. AIM: To demonstrate the potential of the microarray expression assay method in clinical oncology, to describe the history of elaboration, evolution, the principle of the method and possibilities of application of expression microarrays at the current stage of clinical oncology development. MATERIALS AND METHODS: The study was carried out at Ryazan State Medical University. The review included sources found in PubMed, Google Scholar, and eLibrary using the query ‘expression microarrays’ and ‘molecular genetic technologies in oncology’. A total, of 126,455 results were found for the query ‘expression microarrays’ in PubMed and Google Scholar. Thirty-five articles were selected, after a relativity analysis of the sources. A total, of 613 results were found in the eLibrary system for the query ‘molecular genetic technology in oncology’, and 15 articles were selected. Thus, 49 articles were included in the final version. CONCLUSION: The advent of microarray technology marked a new stage in molecular genetic analysis. This method allows simultaneous analysis of hundreds of transcription products and even the entire transcriptome, which together with the data on functions of tumor proteins already opens wide horizons for the use of this technology in clinic. Accumulated data allow to see a wide perspective in this method in terms of analysis of expression profile, metastatic potential of tumors, differential diagnosis between different types of malignant neoplasia, and thus individualize the treatment approach for each individual patient. In our opinion, expression profile analysis is an area promising for further, even more detailed study and discussion within the framework of clinical oncology.