Our view refer 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 ones. 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(25) serum samples were serologically and the second group (75) negative (healthy) cows. Hematological analysis revealed normocytic anemia and Lymphopenia. Biochemical analysis of brucella positive serum infected cows when compared with negative control revealed observed elevation in (AST), (ALT), (ALP) and (GGT) activity in addition to non-significant increases in creatinine level and significant decrease in serum urea in diseased cows. Total protein, α1 globulin,β2 globulin recorded significant decrease while non sig change were observed in α2 ,β1 andγ globulin in infected group. Immunologically IL-1 β and IL-10 showed significant elevation in infected group.