Classical Hodgkin lymphoma (HL) is a rare hematological cancer, affecting preferentially young adults. Using a risk-adapted approach, HL has become highly curable (>80%) with front-line chemotherapy in addition with radiotherapy, despite long term significant toxicity. Some patients are primary refractory or relapse after first-line chemotherapy, requiring high dose chemotherapy with serious side effects. Studies of the microenvironment from HL tissue reveal ineffective inflammatory and immune cell infiltrate surrounding Reed-Sternberg cells, involving the Programmed cell Death 1 (PD-1)/PD-ligand-1 checkpoint pathways. Recently, immune checkpoint inhibitors demonstrated high efficacy for relapsed and refractory patients, with a favorable safety profile but indeterminate long term outcome. Guidelines for nivolumab or pembrolizumab treatment in HL remain to be established.