Corynebacterium pseudotuberculosis is the etiological agent of caseous lymphadenitis (CLA), a common disease in small ruminant populations throughout the world. Once established, this disease is difficult to eradicate because drug therapy is not effective and because the clinical detection of infected animals is of limited efficiency. We reviewed the microbiological, biochemical and taxonomic features of C. pseudotuberculosis, general aspects of infection, the main virulence determinants and currently available commercial vaccines. We also examined the current molecular strategies for the study of virulence in C. pseudotuberculosis, including the latest research on the identification of novel virulence factors and genes, which will help us to better understand the biology of this microorganism. This knowledge may also contribute to the development of improved CLA vaccines, including subunit and DNA-based types, as well as to improve the diagnosis, treatment and control of this disease.