The IUPHAR/BPS Guide to PHARMACOLOGY (GtoPdb) is an open, expert-driven database that contains information on over 1,700 pharmacological targets and the substances that act on them. The database provides overviews and detailed information on targets that is manually curated from literature and reviewed by experts. It aims to cover human drug targets and potential future therapeutic targets. New features of the database include search tools to find targets and ligands, information on diseases associated with targets and ligands, organization of ligand families, and comparison of ligand activity across species. The database content is available to download in various formats and its interoperability has been increased through developing an RDF version and submitting data to other sources