Our view refers to clarify the seroprevalence of brucellosis infection in dairy cows in Menoufiya Governorate and to evaluate the hematological, biochemical and immunological parameters changes in blood of infected cows compared to healthy group. Blood samples of 100 dairy cows (3-5) years from private farm and Menoufiya abattoir were screened for Brucella infection using (BAPAT) test and groups, the first group consistent of ( 25) samples which serologically positive to brucella and the second group consistent of (75) samples which brucella negative. Hematological analysis revealed normocytic anemia and Lymphopenia. Biochemical analysis of brucella positive serum infected cows when compared with negative control revealed significant elevation in (AST), (ALT), (ALP) and (GGT) activity in addition to non-significant increases in creatinine level, however a significant decrease in serum urea in diseased cows was recorded. Total protein, α1 globulin, β2 globulin revealed significant decrease while non-significant change was observed in α2, β1 and γ globulin in infected group. Immunologically IL-1 β and IL-10 showed significant elevation in infected group when compared with negative control group. Brucella infectionBuffered acidified plate agglutination test.