Recombinant antibodies, including whole antibodies, antibody fragments, antibody fusion proteins or conjugates, and more recently also small antibody mimetics, have found increasing applications as therapeutics, e.g. for the treatment of cancer or inflammatory diseases. While whole antibodies have an exceptionally long half-life, small antibody derivatives often suffer from rapid elimination from the circulation. In order to improve administration and therapeutic efficacy, modifications to extend the plasma half-life have been developed and implemented in these antibody formats. This review provides a comprehensive summary of the various strategies currently available to extend plasma half-lives of recombinant antibodies.