Gene sequencing of 16S, 18S, and ITS regions is a crucial tool in molecular diagnostics, especially in microbiology, pathology and forensic medicine. These genes contain conserved and variable regions and are widely used for the taxonomic classification of bacteria and eukaryotes. Sequencing of 16S rDNA helps detect bacterial infections, while sequencing of ITS regions and 18S rDNA is used to identify fungal or parasitic infections, especially when traditional methods are ineffective. This article focuses on the expanded possibilities of these methods, their application in clinical diagnostics and research, their advantages and disadvantages, and discusses potential future developments in the field of next-generation sequencing (NGS) technology.