This study was carried out to reveal the importance of procalcitonin, C reactive protein, nitric oxide levels, and adenosine deaminase activity in the diagnosis and prognosis of the disease in naturally infected sheep with Babesia ovis. Thirty sheep diagnosed clinically and parasitologically as having Babesia ovis were allocated to 2 groups. The first group was treated only with imidocarp dipropionate and the second group with imidocarp dipropionate and flunixine meglumin. On the seventh day after treatment, blood samples were collected again from the sheep in the babesiosis-infected group and the treatment responses were assessed. Serum PCT (1.72 +/- 0.34 ng/mL, P < 0.01), CRP (101.42 +/- 11.73 mu g/mL, P < 0.001), NO (15.77 +/- 2.75 mu mol/L, P < 0.01), and ADA (13.92 +/- 0.88 IU/L, P < 0.01) were higher in sheep with babesiosis than in the healthy sheep (0.49 +/- 0.04 ng/mL, 49.46 +/- 4.57 mu g/mL, 8.15 +/- 0.63 mu mol/L, 9.34 +/- 1.19 IU/L, respectively). When PCT, CRP, NO, and ADA before treatment and after treatment in the infected sheep were compared, the levels of these parameters except for ADA in the second group were determined to have statistically decreased after the treatment. As a result, it has been concluded that the measurements of PCT, CRP, NO, and ADA in sheep with babesiosis may be useful for the diagnosis and prognosis of the disease when assessed in association with clinical examination.