Imatinib mesylate (GleevecTM, formerly known as STI571) is an oral drug that selectively inhibits bcr-abl, c-kit and platelet-derived factor receptor (PDGFR) tyrosine kinase. It has been used for treating chronic myelogenous leukemia (CML) and gastrointestinal stromal tumors. Various adverse cutaneous reactions have been reported, yet the development of psoriasis or a psoriasiform drug eruption by the drug has rarely been reported. We herein report on a case of psoriasiform drug eruption that developed after administering imatinib mesylate to treat CML. (Korean J Dermatol 2009;47(5):722∼725)