Biologics are relatively new drugs developed through modern monoclonal antibody techniques and became more familiar to some disease treatments such as Rheumatoid arthritis, psoriasis, ankylosing spondylitis, ulcerative colitis, malignant lymphoma, SLE and lupus nephritis. Some case reports shows development of leprosy during/after biologics treatment and success treatment of ENL with biologics. Collection of reports was done through web search by using document retrieval engine such as Pub-med and ProQuest. 7 cases of development of leprosy with biologics and 2 cases of ENL treatment with biologics and they were reported in the mini-symposium of Annual academic meeting of Japan Leprosy association. The widespread use of biologics reminds us of development of some infectious diseases as a side-effect and leprosy might be one of them. Because number of the reports was still very limited, we cannot go to further discussion at this moment. Accumulation of reported cases will lead the detailed information about correlation between biologics and leprosy, either on effectiveness or on adverse ones.