Abstract: Objective 　Evaluate the impact of SEA and MDP on effectiveness of osteosarcoma fussion cell vaccine. Methods 　Tritiated thymidine (³ H-TdR) incorporation and ⁵¹ Cr release assays were used to detect the influence of SEA on T cell proliferation and CTL cytotoxic activity induced by osteosarcom fussion cells vaccine. And the treatment effectiveness was examined when the tumor vaccine was used simultaneously with SEA and MDP. Results 　SEA obviously enhanced the T cell proliferation and CTL cytotoxic activity induced by osteosarcoma fussion cell vaccine. And the result s f rom animal model showed that the average tumor weight s and incidence of lung metastasis were decreased dramatically when the SEA or MDP was administered simultaneously with osteosarcom fussion cell vaccine. Conclusion 　SEA or MDP can be used as adjuvant to facilitate the anti-tumor immunity induced by osteosarcoma fussion cell vaccine.