Brucella is a zoonotic, intracellular pathogen that causes a severe infectious disease called brucellosis in both animals and humans. The disease is transmitted from animal reservoirs to humans via (i) direct contact with infected materials; (ii) inhalation of infectious aerosols; and (iii) ingestion of contaminated food or water. Clinical symptoms of human brucellosis range from fever, chills, sweats, weakness, myalgia, arthralgia, depression, anorexia, spondylitis, endocarditis, to meningoencephalitis. Laboratory diagnosis of brucellosis has traditionally relied upon in vitro culture isolation of Brucella bacteria followed by various biochemical and serological tests. Recent development of molecular techniques such as PCR has facilitated rapid, sensitive and specific detection of Brucella organisms. Despite continuous efforts in the past decades, there is still a great deal of unknowns about molecular mechanisms of Brucella infection. Future research in this and related areas will help uncover new details on Brucella pathogenesis at molecular level, and lead to novel control and prevention strategies against brucellosis.