Germline mutations in the BRCA1, BRCA2 and Fanconi anaemia genes confer cancer susceptibility, and the proteins encoded by these genes have distinct functions in related DNA-repair processes. Emerging evidence indicates that these processes are disrupted by numerous mechanisms in sporadic cancers. Collectively, there are properties that define 'BRCAness' — that is, traits that some sporadic cancers share with those occurring in either BRCA1- or BRCA2-mutation carriers. These common properties might have important implications for the clinical management of these cancers.