The present invention is directed to novel artificial T helper cell epitopes (Th epitopes) designed to provide optimum immunogenicity when used in peptide immunogens comprising B cell epitopes or peptide haptens, a target antigenic site of a target antigen for eliciting antibodies thereto. The artificial Th epitopes are covalently linked to the target antigenic site and optionally an immunostimulatory sequence to provide effective and safe peptide immunogens.