Acute Leukemia is the most prevalent malignancy of childhood, globally. Immunophenotyping by flowcytometry has developed as an important technique for its outstanding contributions in diagnosis and management of leukemia patients. Objective: To determine the frequency and immunophenotyping by flowcytometry of Acute leukemia in pediatric age group. Methods: The study was conducted at The University of Child health sciences and Children’s Hospital, Lahore from July-2021 to Feb-2022. Data were gathered from 101 consecutive patients, of age from 0.5 to 15 years, that had acute leukemia immunophenotyping using flowcytometry. Results: Flowcytometric immunophenotyping of 101 leukemia patients over 8-month period showed that 67.3% and 33.6% male were females respectively. AML, T-ALL, and B-ALL prevalence was highest in patients with 5 to 10 years of age. Out of 101 leukemia patients, 16 (15.8%) and 85 (84.1%) had AML and ALL diagnosis respectively. Of these 85 ALL cases, 72 (84.7%) were B-ALL and 13 (15.2%) were T-ALL. Study founded that most frequent CD markers in B-ALL, were CD79 and CD19 (100%) whereas CD3 and CD5 in T-ALL and CD13 (93.8%) and CD34 (87.5%) in AML. CD34 was a common marker among B-ALL, T-ALL and AML. Among B-ALL and T-ALL, AntiTdt was a common CD marker whereas HLA-DR was common among AML and B-ALL. Conclusions: Results of Acute leukemia immunophenotyping were homologous to worldwide published research. For accurate leukemia lineage, immunophenotyping of AML and ALL is essential since, if therapy is started based solely on morphological diagnosis, approximately 25% of patients may not respond or recure.