Background. The blastic crisis of chronic myeloid leukemia (CML-BC) is usually the final phase of the disease, in which the percentage of the young, often undifferentiated cells, known as blastocytes gets above 20%. Nowadays, in the era of the therapy with Tyrosine Kinase Inhibitors, the transformation from CML to CML-BC occurs much later and more rarely. Case report. We present the case of a 71 year old male, admitted in July 2017, to the Haematology Unit of Mures County Emergency Hospital presenting severe anemia, leukocytosis, leukocyte left shift, absence of the leukemic hiatus and thrombocytopenia. Splenomegaly (7 - 9 cm) was also found. Cytogenetic examination revealed the presence of Philadelphia chromosome and real-time PCR showed 87% positivity for BCR-ABL. Chronic Myeloid Leukemia was the diagnosis and treatment with Dasatinib was initiated. A month after the patient develops severe thrombocytopenia and hemorrhagic purpura. Treatment was interrupted until the platelet count was restored and continued after with smaller dosage. Erythrocyte mass was transfused in order to correct the anemia. Three months after the diagnosis with CML, spleen expansion and hyperleukocytosis was observed. The peripheral blood smear indicated high blastocyte percentage (88%) and the patient was admitted and diagnosed with CML-BC. The diagnosis was confirmed, RT-PCR still showed positivity for BCR-ABL in 48%. Induction treatment for Acut Lymphoblastic Leukemia with adapted protocol for elderly patient with comorbidities was initiated. In December 2017 the patient refuses further treatment and unfortunately passes away. Conclusion. Chronic myeloid leukemia is a condition with a high survival rate, especially after introducing the tyrosine kinase inhibitors, but when the blastic transformation occurs, many patients are lost due to infections and hemorrhagic complications.