Abstract: Background: In case of chronic infection and cancer, T cells occur dysfunction as a result of prolonged antigen exposure, and have a reduced ability to clear pathogens or to eliminate cancer cells. Insights have recently been gained into the role of receptors that negatively regulate T cells which promote T cell dysfunction. Lymphocyte activation gene-3 protein ( LAG3，also known as CD223 ) , a inhibitory receptor, come into notice. Objective: To evaluate the therapeutic potential of targeting the LAG3 in the situations such as chronic infection and cancer. Content: The paper focuses on the inhibitory receptors LAG3, and summarize from clinical trails and discuss the potential mechanism of immune cells. Trend: In the tumor environment, the known features and functions of LAG3 make it an appealing target for immune modulation, including its well-established role in the negative regulation of T cell function. LAG3 may also have multiple roles in immune regulation. In the studies of the oncotherapy, how to make use of the immune mechanism of LAG3, suppress the proliferation of tumor cells, and take the effect of LAG3 blockage in patients remains to be seen.