The database of Cancer Passenger Mutations (dbCPM) is a highly curated database of passenger mutations that are unlikely to engage in cancer development, progression, or therapy. dbCPM currently contains 941 experimentally supported and 978 putative passenger mutations derived by manual curation of literature. The database is organized to provide informaton about cancer passenger mutations and interpretations in a consistent way, as well as allowing users to submit entries. It can be a valuable resource for clinical researchers and also a benchmark database for development and evaluation of methods for predicting the effects of cancer mutations.