The molecular biology laboratories that perform the RT-qPCR test to measure BCR-ABL1 using techniques that are not harmonized to international scale, run the risk of reporting an erroneous result. This deficiency, added to the lack of consensus regarding the interpretation of the test results, generates confusion between doctors and patients, which inevitably leads to sub-optimal therapeutic decision. We intend to address and solve the need to harmonize molecular methodologies and criteria for the interpretation of results, in order to guarantee more effective clinical decision.