Inthis study, we found that intratumoral injection of λ-carrageenan couldinhibit tumor growth in B16-F10 and 4T1 bearing mice and enhance tumor immuneresponse by increasing the number of tumor-infiltrating M1 macrophages, DCs and moreactivated CD4+CD8+ T lymphocytes in spleen. This evidence concerns the gene CD4 and neoplasm.