Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by excessive accumulation of apparently normal myeloid cells and the Philadelphia chromosome resulting from t(9;22) reciprocal chromosomal translocation and leading to BCR-ABL fusion gene formation. Bone marrow puncture (BMP) ofCML reveals hypercellular marrow with a myeloid:erythroid (M:E) ratio ≥ 10:1. CML can transform into acute myeloid leukemia (AML) in some cases. AML is a hematologic malignancy characterized by the clonal expansion of myeloid blasts in the peripheral blood, bone marrow, or other tissues. AML is defined as a ≥ 20% myeloid blast count of 500 bone marrow cells based on BMP. We reported a 56-year-old male who was admitted to Dr. Saiful Anwar General Hospital in Malang on May 23, 2025, with the complaint of weakness. Physical examination showed anemic conjunctiva, subconjunctival bleeding, petechiae on the extremities, and splenomegaly. Complete blood count showed hemoglobin 7.0 g/dL, leukocyte 41,050/μL, and thrombocyte 12,000/μL. BMP showed a proportion of 28% myeloblast, consistent with AML. The patient had a history of CML since April 29, 2024 with BMP result was hypercellular marrow with M:E ratio 15:1, and a BCR-ABL result was 27,5%. Thus, the patient was diagnosed with CML transformation into AML. Conditions predisposing to AML development in this patient were chronic benzene exposure, chronic tobacco smoking, and CML. Thepatient lived near the paper industry in Tulungagung, East Java, Indonesia, since childhood and the waste was often smelled. Benzene is widely used in the paper industry as a solvent, and most benzene exposure occurs through inhalation which induces DNA hypomethylation and promoter hypermethylation, whichfoster leukemogenesis. ± 35-80 μg of benzene is also measured per cigarette. He had a smoking habit before being diagnosed with CML. First-line treatment of CML is a tyrosine kinase inhibitor such as imatinib 400 mg/day for this patient. Chemotherapy for remission induction in AML was refused by the patient.