The paradoxical coexistence of spontaneous tumor antigen-specific immune response with progressive disease in cancer patients need to dissect the molecular pathways involved in tumor induced T-cell dysfunction or exhaustion. Programmed cell death 1 (PD-1) has been identified as a marker of exhausted T cells in chronic disease states, and blockade of PD-1-PD-L1 interactions has been shown to partially restore T-cell function. We have found that T-cell immunoglobulin mucin (Tim) 3 is expressed on CD8(+) tumor-infiltrating lymphocytes (TILs) isolated from patients with colorectal cancer. All T-cell immunoglobulin mucin 3 (Tim-3(+)) TILs coexpress PD-1, and Tim-3(+) PD-1(+) CD8(+) TILs represent the predominant fraction of Tcells infiltrating tumors. Tim-3(+) PD-1(+) CD8(+) TILs exhibit the most severe exhausted phenotype as defined by failure to produce cytokines, such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-2. We further find that combined targeting of the Tim-3 and PD-1 pathways increased the frequencies of not only interferon-gamma and tumor necrosis factor-alpha but also frequencies of proliferating tumor antigen-specific CD8(+) T cells than targeting either pathway alone. A concomitant decrease in regulatory T cells and enhanced killing in a cytotoxicity assay was observed. Collectively, our findings support the use of Tim-3-Tim-3L blockade together with PD-1-PD-L1 blockade to reverse tumor-induced T-cell exhaustion/dysfunction in patients with colorectal cancer.