While the transformation from myelofibrosis to CML is unusual, this case report illustrates an unusual transformation of myelofibrosis to CML, marked by the emergence of a BCR-ABL1-positive clone detectable by fluorescence in situ hybridization (FISH) but not by polymerase chain reaction (PCR). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.