The article provides an overview of the taxonomy and clinical significance of *Nocardia* species, which are a group of bacteria that can cause a range of infections in humans. The genus *Nocardia* currently includes over 50 species, many of which are recognized human and/or animal pathogens. The article discusses the taxonomic history and current molecular definitions of *Nocardia* species, highlighting the controversy surrounding the nomenclature of *Nocardia asteroides*. It also describes the clinical manifestations of nocardial infections, including pulmonary disease, extrapulmonary disease, primary cutaneous disease, catheter-related infections, and healthcare-associated disease. The importance of antimicrobial susceptibility testing for effective treatment is emphasized, and various laboratory methods for identifying *Nocardia* species are outlined, including microscopic and macroscopic direct examination, biochemical methods, chemotaxonomic methods, serological methods, and molecular techniques such as 16S rRNA gene sequencing and PCR-RFLP analysis. The article concludes with a discussion of the clinical significance of *Nocardia* infections and the need for accurate species identification for appropriate treatment.The article provides an overview of the taxonomy and clinical significance of *Nocardia* species, which are a group of bacteria that can cause a range of infections in humans. The genus *Nocardia* currently includes over 50 species, many of which are recognized human and/or animal pathogens. The article discusses the taxonomic history and current molecular definitions of *Nocardia* species, highlighting the controversy surrounding the nomenclature of *Nocardia asteroides*. It also describes the clinical manifestations of nocardial infections, including pulmonary disease, extrapulmonary disease, primary cutaneous disease, catheter-related infections, and healthcare-associated disease. The importance of antimicrobial susceptibility testing for effective treatment is emphasized, and various laboratory methods for identifying *Nocardia* species are outlined, including microscopic and macroscopic direct examination, biochemical methods, chemotaxonomic methods, serological methods, and molecular techniques such as 16S rRNA gene sequencing and PCR-RFLP analysis. The article concludes with a discussion of the clinical significance of *Nocardia* infections and the need for accurate species identification for appropriate treatment.