A preliminary study was conducted in which polycolonal antiser­um against bovine viral diarrhoea virus (BVDV), was prepared in New­zeland white rabbit. The antibodies were titrated by both serum neutrali­zation test (SNT) and enzyme linked immunosorbent assay (ELISA) techniques. The immunoglobuline was precipitated from the serum by con­centrated ammonium sulphate solution and was conjugated with fluores­cine isothiocyanate (FITC). Both non-reacted FITC and heavily FITC con­jugated immunoglobuline were removed. The optimal dilution of the conjugate and its specificity were determined by using BVDV infected tissue cultures. Seventy-five bovine tissue specimens collected from Cairo abat­toir were used for BVDV isolation, as well as for direct fluorescence anti­body (FA) techniques and their results were compared.