This study was carried out to determine the frequency of expression of BCR-ABL1 fusion transcript variants in Sudanese CML patients by using RT-PCR, and was partly motivated by the introduction of imatinib mesylate, whose administration is currently based on the molecular diagnosis of BCR-ABL1 fusion genes. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.