Recent advances in high‐throughput sequencing technologies have unexpectedly revealed that somatic mutations of splicing factor genes frequently occurred in several types of hematological malignancies, including myelodysplastic syndromes, other myeloid neoplasms, and chronic lymphocytic leukemia. Splicing factor mutations have also been reported in solid cancers such as breast and pancreatic cancers, uveal melanomas, and lung adenocarcinomas. These mutations were heterozygous and mainly affected U2AF1 (U2AF35), SRSF2 (SC35), SF3B1 (SF3B155 or SAP155), and ZRSR2 (URP), which are engaged in the initial steps of RNA splicing, including 3′ splice‐site recognition, and occur in a large mutually exclusive pattern, suggesting a common impact of these mutations on RNA splicing. In this study, splicing factor mutations in various types of cancers, their functional/biological effects, and their potential as therapeutic targets have been reviewed. WIREs RNA 2014, 5:445–459. doi: 10.1002/wrna.1222This article is categorized under: RNA Processing > Splicing Mechanisms