During the development of effective and safe antibody-drug conjugates some technical issues arose. The generation of an appropriate chemical linkers between the monoclonal antibody and the cytotoxic drug turns out to be a major difficulty. This is due to the complex synthesis of linker chemistry. On the other hand, the design of types of linkers is highly dependent on the target cells biology, the antibody characteristics, and the molecule structure of the drug. With the development of ADCs introduced to clinical trials or approved by the FDA, a series of typical linkers are now in use. https://www.creative-biolabs.com/adc/linker-module.htm