The tumor microenvironment in B-cell non-Hodgkin lymphoma (NHL) comprises not only malignant cells but also significant numbers of normal immune cells. The intratumoral immune infiltrate includes T-lymphocytes that appear to target the malignant clone. Despite immunologically recognizing the lymphoma cells, the intratumoral T-cells are unable to eradicate the malignant cells and the lymphoma commonly progresses. Recent data has identified mechanisms whereby activated intratumoral T-cells are suppressed or become exhausted due to chronic antigen stimulation. A clearer understanding of these mechanisms will allow for strategies to overcome them and improve the outcome of patients with lymphoma.