Immunotherapy is a promising therapeutic strategy in the treatment of lymphoma. The programmed death-1 (PD-1)/PD-ligand immune checkpoint pathway has been manipulated by tumor cells and serves as a mechanism of tumor evasion from the anti-tumor immune response. The recent development of anti-PD-1 antibodies has offered a therapeutic strategy for restoring the function of exhausted antigen-specific T cells and enhancing the endogenous anti-tumor immunity. We review the clinical studies demonstrating efficacy and safety of PD-1 antibodies in relapsed/refractory Hodgkin, follicular, and diffuse large B cell lymphoma. Principles learned in the development of immune checkpoint blockade provide the foundation for immunotherapy under clinical investigation.