Because the clinical signs of the brucellosis in small ruminants are not patognomonic and therefore diagnosis based on clinical symptoms is nontennable, additional laboratory tests are used for diagnostic of Brucella disease. Laboratory tests involve identification of the causative microorganism by classical laboratory techniques for isolation of Brucella spp. or PCR (Polymerase Chain Reaction) and measuring of the immune responses. Animals infected with Bruce/la spp. are usually diagnosed by serological tests, which measure the humoral immune response. Beside the humoral response, the infection with Bruce/la spp elicits cell-mediated immune response which can be detected by allergic skin test. Evaluation of the role of the cellmediated immune response in infection by Bruce/la spp. and its detection, using delayed type of hypersensitivity reaction, is described in this paper.