The aim of the study was to evaluate acute phase response via Haptoglobin and serum amyloid-A concentrations in dairy cows naturally infected with Anaplasma marginale. The second aim of the study was to determine the changes in clinical, hematological and biochemical parameters in dairy cows naturally infected Anaplasma marginale. A total of 40 dairy cattle suffering from bovine anaplasmosis were included to the study from a dairy cattle herd. A total of 10 healthy dairy cattle were selected for control group. Analysis of acute phase proteins, hematologic analysis and biochemical analysis was performed in this study. Serum haptoglobin and serum amyloid-A concentrations significantly increased in cattle infected with Anaplasma marginale compared to healthy cattle. All cattle in infected group demonstrated clinical signs of anaplasmosis. Significantly decreased red blood cell count, packed cell volume, and hemoglobin concentration were observed in infected cattle compared to the control group. Serum aspartate aminotransferase, alkaline phosphatase, creatinine and bilirubin concentrations were significantly increased in infected cattle compared with the control group. In conclusion, the changes of biochemical and hematological parameters may be indicate of anemia and tissue damage in cattle with anaplasmosis. Serum haptoglobin and serum amyloid-A concentrations could be usefull in evaluate of acute phase response in cattle infected with Anaplasma marginale.