Drug transporters play a key role in the absorption, distribution, and elimination of many drugs, and they appear to be important determinants of therapeutic and adverse drug activities. Although a large body of data pertaining to drug transporters is available, there are few databases that inform drug developers, regulatory agencies, and academic scientists about transporters that are important in drug action and disposition. In this article, we inform the scientific community about the UCSF-FDA TransPortal, a new and valuable online resource for research and drug development.