Imatinib mesylate (IM) represents the first-line treatment of patients with chronic myeloid leukemia (CLM) or gastrointestinal stromal tumor (GIST). It presents several side effects. However, less than 10% are nonhematologic including nausea, vomiting, diarrhea, muscle cramps, and cutaneous reactions. The aim of our study was to identify data regarding IM cutaneous adverse effects (AEs) to improve the clinical diagnosis and management of the more frequent side effects. Skin examination should be done before and during IM treatment so that AEs can be diagnosed and treated early with less impact on chemotherapy treatments and on the quality of life of the patient.