Breakpoint cluster region-Abelson (BCR-ABL1) translocation is the characteristic sign of chronic myeloid leukemia (CML). The quantitation of BCR-ABL1 messenger RNA is requisite for patients with CML, and reverse-transcription real-time quantitative polymerase chain reaction (RQ-PCR) is the method used most extensively in testing laboratories worldwide. Nevertheless, substantial variation in RQ-PCR results from different laboratories makes interlaboratory comparability inconvincible owing to the lack of standardization. To facilitate interlaboratory comparative assessment and international standardization, an international scale (IS) for BCR-ABL1 was proposed. The laboratory-specific conversion factors derived from the IS can convert local different values to the IS without changing procedures. The standardization of BCR-ABL1 also includes the whole analytical process, so it is noteworthy to pay attention to the quality control before BCR-ABL1 quantitative analysis. More importantly, the World Health Organization has validated a first genetic reference panel which is limited to the manufacturers to produce and calibrate secondary reference reagents. Also, a certified reference plasmid, ERM-AD623, was internationally accepted. This article mainly focuses on BCR-ABL1 measurement and these standardization efforts in progress.