Antibody-drug conjugates (ADCs) for tumor therapy contain a cytotoxic drug conjugated to a monoclonal antibody (mAb) across a linker. A homing device, the mAb enables the recognition of tumor cells by binding to tumor-specific antigens. The linker is usually cleaved inside the tumor cell or close to the cell surface according to a well-designed chemical mechanism or upon in vivo degradation of the immunoglobulin moiety. The potent drug load is then released exerting its cytotoxic activity within the target cell or in its close proximity (bystander effect). This concept enables a highly selective approach to minimize side effects for the patient. In August 2011, Seattle Genetics' ADC Adcetris® (brentuximab vedotin) was approved by the US FDA. This review gives background information on this interesting new technology and presents the relevant, recent patents in this research area. patents by Seattle Genetics, Immunogen and Biotest are discussed owing to their eminent contribution and relevance to the field.