Imatinib mesylate has been identified as a tyrosine kinase inhibitor that selectively inhibits Abl tyrosine kinases, including Bcr-Abl. It exhibits many polymorphic forms, with the most stable and commercialized polymorphs known as the α and β forms. In the present study, the compatibility between the polymorphs of Imatinib mesylate and selected excipients (MCC, HPMC, PVPP, SiO