Brucellosis is a zoonotic disease that affects a large number of people and animals, causing physical disability, workforce loss and significant economic losses in the livestock industry. In the current study, it was aimed to determine and compare the levels of tumor necrosis factor alpha (TNF–α), interferon gamma (IFN–γ), Procalcitonin (PCT) and Neopterin in the blood serums of cattle with brucellosis and vaccinated against brucellosis. The materials of this study consisted of a total 48 blood serums belonging to three basic groups, each consisting of 16 animals. Disease group (1st group) were divided into two subgrups each consisting of 8 animals that 21st day after abortion and seropositive 7 months pregnant, the vaccinated (2nd group) and the control (3rd group) groups were divided into two subgroups, each consisting of 8 animals that gave birth 21 days ago and 7 months pregnant. IFN–γ and PCT levels were determined by sandwich enzyme immunoassay, TNF–α and Neopterin levels were determined using competitive inhibition enzyme immunoassay method by using ELISA device. In this study, TNF–α, PCT and Neopterin levels measured in the blood serums of the Brucella seropositive (1st), conjunctival Brucella abortus S19 vaccine administered (2nd) and unvaccinated Brucella seronegative control groups were compared and no significant difference could be determined between the subgroups of the groups (P>0.05). There were a significant differences between 1st, 2nd, and 3rd groups (P<0.05). IFN–γ levels determined in the blood serums of 1st, 2nd and 3rd groups were compared and nosignificant differences were found between the subgroups of 2nd and 3rd groups (P>0.05), but there were a significant differences between the subgroups of the 1st group (P<0.05). Similarly, a significant differences were determined between 1st, 2nd and 3rd groups in terms of IFN–γ levels (P<0.05). As a result, it was thought that detecting very high serum TNF–α, IFN–γ, neopterin levels in cattle with brucellosis would be helpful in the diagnosis and follow–up of brucellosis. However, it was concluded that there is a need for controlled studies comparing more herds with brucellosis to determine whether the relevant cytokines can be used in the diagnosis of brucellosis.