Imatinib mesylate (IM) therapy leads to a complete cytogenetic response (CCyR) in 75-90% of Chronic Myeloid Leukemia (CML) patients in chronic phase, but only a small percentage of patients achieve complete molecular response (CMR). Very little is known about IM discontinuation. We report the case of a 20-years-old male patient in chronic phase CML who maintained undetectable BCR/ABL mRNA levels, despite IM discontinuation over a period of 15 months after achieving CMR. Our patient reached CCyR and CMR after 3 and 6 months of IM treatment, respectively. We also reviewed the published literature concerning cases of IM discontinuation.