c-KIT is a proto-oncogene that encodes a type III transmembrane tyrosine kinase. c-KIT and its ligand stem cell factor have a key role in survival, proliferation, differentiation and functional activation of hematopoietic progenitor cells. c-KIT mutations are reported in the majority of systemic mastocytosis cases. c-KIT mutations account for 20% to 40% in core-binding factor (CBF) acute myeloid leukemia (AML). c-KIT mutations also occur in MDS and contribute to MDS risk stratification. c-KIT mutation in AML confers increased risk of relapse and decreased overall survival. Tyrosine kinase inhibitors, such as imatinib and avapritinib, have been evaluated to treat systemic mastocytosis. Imatinib has also been evaluated to treat c-KIT-positive AML and MDS, and it has been found effective as a single reagent or combination therapy.