We present here a case of our patient who fulfilled all the WHO 2008 diagnostic criteria of CMML (see Section 1), namely, persistent peripheral blood monocytosis 1.9–13.6 × 109/L for more than 4 months, no Philadelphia chromosome or BCR-ABL1 fusion gene by FISH, chromosomal analysis by banding technique or PCR, and no rearrangement of PDGFRA or PDGFRB, with 4% blasts (including promonocytes) of the BM and with all other causes of monocytosis being excluded. This evidence concerns the gene BCR and chronic myelomonocytic leukemia.