The aim of this study was to measure the acute phase response of cattle with trichophytosis by determining the serum concentrations of serum amyloid A (SAA) and haptoglobin (Hp) and also to investigate how Nigella sativa could affect Hp and SAA levels. In this study, 16 cattle (7-12 month old, Holstein and Montofon breed) with clinically and microbiologically diagnosed trichophytosis and 8 healthy cattle (7-12 months old, Holstein and Mondofon breeds) were used. The animals in the study were divided into 3 groups; control group (Group 1, n= 8), NS treated group (Group 2, n= 8, were administered topically once daily for two weeks) and untreated group with trichophytosis (Group 3, n= 8). Concentrations of serum Hp and SAA were measured using commercially available ELISA kits. Before the treatment, SAA and Hp levels were significantly higher (P<0.05) in cattle with trichophytosis when compared to controls respectively; 36.05±0.28 mg/L, 38.19±0.35 mg/L and 9.43±0.11 mg/L; 0.354±0.018 g/L, 0.328±0.023 g/L and 0.084±0.007 g/L. Fourty eight hours after NS application to the cattle with trichophytosis, SAA and Hp levels were significantly lower (P<0.05) in Group 2 than Group 3 respectively, 18.34±0.52 mg/L, 32.26±0.52 mg/L and 0.103±0.016 g/L, 0.284±0.024 g/L. It was concluded that the elevated values of Hp and SAA were a result of the inflammatory response to dermatophytosis. Also in NS group, it is thought that the decreases of Hp and SAA levels may be caused by the antiinflammatory effect of NS.