Immunophenophenotyping plays a major role in characterization of blasts in Chronic myeloid leukemia– Blast crisis (CML–BC). This study evaluated total 52 cases of CML–Blast crisis in which thirty–two (61.5%) cases were of myeloblastic crisis and twenty (38.5) cases of lymphoblastic crisis. Predominant myeloid markers were CD33 (97%), cd13 (94%), CD117 (75%) and MPO (59%). Predominant lymphoid markers were CD19 (100%), CD79a (95%) and CD10 (80%). This differentiation has a very important role in patient management and outcome.