We examined function of Tim3/Gal9 in various cells from osteosarcoma patients. Tim3 T cells presented low proliferation and could be reverted by blocking Tim3/Gal9. Tim3 CD4+ T cells secreted more IFNγ but were vulnerable to Gal9-mediated suppression. Tim3 was associated with high IL-10 and low IL-12 in monocyte. Tim3+ monocytes inhibited IFNγ expression from total CD4+ T cells through Gal9.