The present invention discloses methods for polymerizing non-immunogenic haptens into immunogens, which then can be used to stimulate anti-hapten antibody production in animals. Specifically, haptens with amine and/or carboxylic groups are polymerized into macromolecules by using cross-linking reagents, and the derived haptenic polymers are used to immunize animals for the production of anti-hapten antibodies.