Background and aim: Brucellosis is a worldwide disease. Specific diagnosis of brucella is performed by culture, serological, and molecular tests. Serological tests are most commonly used in the diagnosis because of the difficulty bacterial growthing in culture. The present study aimed to identify the relation between brucellosis and mean platelet volume (MPV), as well as to investigate the correlation with other parameters used to determine the activation of the disease. Materials and methods: Forty-eight brucellosis patients and 30 aged and gender-matched controls were enrolled. Patient group was determined based on standard tube agglutination test as well as concurrent MPV, thrombocyte count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). Results: There was no significant difference between the patients and controls in terms of age and gender. Significant differences were observed between the groups in terms of MPV, thrombocyte count, ESR and CRP. While no significant correlation was determined between MPV and ESR, there was a significantly negative but weak correlation with CRP and thrombocyte count. Conclusion: MPV may be a low-cost indicator for brucellosis when together with other parameters. However, further studies are needed to evaluate the relation between MPV and brucellosis.