The T cell receptor (TCR) repertoire reflects the status of the cell mediated adaptive immune response. In the field of cancer immunotherapy, the TCR repertoire is expected to act as a biomarker for anti-tumor and auto-immune T cell responses following therapeutic interventions. However, the immunological significance of changes in the TCR repertoire in tumor-bearing hosts remains elusive. In this study, we used unbiased TCR gene amplification and an Ion Proton next generation sequencer to conduct high throughput TCR sequencing on CD8+ T cells sorted from the tumor, blood, and draining lymph node (dLN) in a B16F10 mouse melanoma model. Analysis of V/J segment usage and clonotype frequency revealed skewed V/J segment usage and oligoclonal expansion in the TCR repertoire of tumor-infiltrating T cells compared to T cells in the blood and dLN. By tracking clonotypes in individual mice, we found that only a small number of selected clonotypes from the dLN or blood were enriched in the tumor. Overlapping clonotypes could be categorized into four groups based on their frequencies in the dLN and tumor: dLNminor/tumorminor, dLNmajor/tumorminor, dLNminor/tumormajor, dLNmajor/tumormajor. After anti-CD4 monoclonal antibody treatment, which enhances anti-tumor CD8+ T cell responses by depleting of immune suppressor cells including regulatory T cells, we observed an increase in the diversity and combined frequency of clonotypes that were overlapping between the tumor and the dLN or the tumor and the blood. Furthermore, anti-CD4 antibody treatment increased the frequency of the dLNmajor/tumorminor and the dLNmajor/tumormajor clonotypes. Our analysis of overlapping clonotypes between organs provides an immunological basis for interpreting changes in the TCR repertoire following cancer immunotherapy.