This study will recruit approximately 100 CML patients under imatinib therapy in complete molecular remission with a history of at least 18 months of consecutive negative standard Q-RT-PCR as performed in their own centers. After signing the informed consent form (ICF), the patients will be tested for dPCR and will discontinue imatinib therapy. Then they will be monitored by standard Q-RT-PCR to assess the maintenance of the molecular remission; collection of data will be prospective as each center will collect the data for 36 months. At the end of this period, a peripheral blood sample for dPCR analysis will be obtained from those patients who will still have undetectable BCR-ABL transcripts by Q-RT-PCR to verify CML eradication. The maintenance of molecular remission by Q-RT-PCR and the survival will be monitored every six months during an additional follow-up of 24 months. Patients found to be positive to BCR-ABL transcripts by standard Q-RTPCR will repeat the test every 2 to 4 weeks until the loss of molecular remission, defined as two consecutive BCR-ABL positive tests with at least one with BCR-ABL/BCR value above 0.1%, or until the end of the study, whichever come first.