Evaluation of in vitro spontaneous apoptosis of acute leukemic blast cells after incubating for different time period and its correlation with clinical outcome is well documented in the literature. However, there is insufficient information available on the flowcytometric determination of cell viability immediately after separating blast cells and its correlation with the clinical response. In this study, we attempted to evaluate the relationship between viability of freshly isolated leukemic cells and the clinical response. Cell viability was evaluated in freshly isolated leukemic cells from 84 patients with acute leukemia (AL) using 7-Amino-Actinomycin D and was correlated with the clinical response following induction chemotherapy. Patients with ALL who achieved complete remission (CR) had significantly lower mean live cell (70.9%) compared to those patients who did not achieve CR (93.3%) (p=0.02). Furthermore, ALL responders had also significantly higher mean early apoptotic cell (19.4%) as compared to non responders (5%) (p=0.04). No significant difference was found in the mean live / early apoptotic cell count of responders and non responders of AML patients. The probability of obtaining CR in ALL patients was 3.7 and 2.7 times higher in those who had mean live cell count less than 70% and apoptotic cell count more than 10%, respectively. A lower cell viability and higher apoptosis in freshly isolated leukemic cells at the time of diagnosis may indicate a favorable response in patients with ALL but may not provide any sufficient information in predicting the response in AML patients to induction chemotherapy.