We determined the adjuvant activity of five commercially available endodontic sealers : Apatite Root Sealer Type-1 (Sankin), Canals (Syouwa), Tubli-Seal (Kerr), Sealapex (Kerr) and Dentalis KEZ (Neo). Keyhole limpet hemocyanin (KLH) served as antigen. Three of the sealers (Type-1, Canals and Tubliseal) were potent adjuvants in increasing the antibody response to KLH in C57BL/6 mice. although they did not induce IL-2 in serum. KEZ and Sealapex were not potent adjuvants in increasing IgG response to KLH, although they were potent in increasing IgM response.