Patulin hemisuccinate (P-HS) was synthesized and conjugated to bovine serum albumin (BSA) as the hapten-protein conjugation for immunization. Polyclonal antibodies were obtained from the antiascites of six immunized mice. Titers and specificity were determined using an indirect ELISA. The results indicated that three of the six mice were better immunized and that the antibodies acted strongly against patulin-hemisuccinate-BSA. Slight ELISA responses of the antibodies against patulin alone showed the potential for developing monoclonal antibodies.