COSMIC curates comprehensive information on somatic mutations in human cancer. Release v48 (July 2010) describes over 136,000 coding mutations in almost 542,000 tumour samples; of the 18,490 genes documented, 4803 (26%) have one or more mutations. Full scientific literature curations are available on 83 major cancer genes and 49 fusion gene pairs. Biomart allows more automated data mining and integration with other biological databases. Annotation of genomic features has become a significant focus. COSMIC integrates many diverse types of mutation information and is making much closer links with Ensembl and other data resources.