Among the livestock populations sheep still now occupies the third position and about 80% sheep is reared by rural farmers in Bangladesh. The sheep in Bangladesh are mainly utilized for meat purposes but also important for good quality leathers and source of income to rural people. One of the infectious diseases, which are a major constraint for sheep productivity, is brucellosis. It is a widely spread disease in the developing countries caused by six species of the bacterial genus Brucella. Bangladesh has been reported as an endemic country for brucellosis because of a considerable number of human and animal populations are exposed to the infection each year. Most cases of brucellosis infection in sheep are inapparent and lack clinical signs. The first evident manifestation is abortion,which frequently occurs 3 to 4 months after gestation. Clinical signs of infected rams are orchitis, hogbacks, anorexia, emaciation, and gradual loss of capacity for hybridization. Other symptoms also include mastitis, bronchitis, and arthritis, among others. This book illustrates the serological diagnosis and epidemiology of brucellosis in sheep and shows a new way of developing the sheep industry.