Conjugates of drugs with a delivery vector targeting human diseases would be a "magic bullet" according to the early vision of Nobel laureate Paul Ehrlich. Molecules that specifically recognize and bind to structures (like membrane proteins) on the surface e.g. of a tumour cell are suitable as such a delivery vector (homing device). The recent years witnessed the regulatory approval of antibody-drug conjugates. Peptides have distinct advantages over proteins: They can have a high drug loading, easily penetrate tissue, and are easily prepared in a homogenous form with straightforward and well-defined conjugation chemistry. Hence, the development of peptide-drug conjugates is currently an important research area in bioorganic chemistry, medicinal chemistry, chemical biology, and biochemistry. Articles dealing with the development of peptide-drug conjugates for targeted delivery in tumour therapy, but also in other contexts will be considered.