Background Acute Lymphoblastic Leukemia (ALL) represents around 70% of pediatric leukemia. In high-income countries, 5-year survival is above 90% but survival in low-and middle-income countries is inferior. Objective: To document the treatment outcome and prognostic factors of Pediatric ALL in Pakistan. Materials and methods: in this descriptive study, all newly diagnosed cases of ALL/LBL from one to 16 years of age enrolled between 1 st January 2012 to 31 st December 2021 were included. The treatment was based on the standard arm of the UKALL2011 protocol. Results: Data of 945 cases of ALL, including 597 males (63.2%) was analyzed. The mean age at diagnosis was 5.73 ± 3.51 years. Pallor was the commonest presentation in 95.2% followed by fever in 84.2% cases. The mean white blood cells count was 56.6 ± 103.4 x10 9/L. Neutropenic fever followed by myopathy was the most common complication during induction. In univariate analysis, high white blood cells count (P=<0.001), intensive chemotherapy (P=<0.001), malnutrition (P=0.007), poor response to induction chemotherapy (P=0.001), delay presentation (P= 0.004), use of steroids before chemotherapy (P=0.023) significantly adversely affected overall survival (OS). Delayed presentation was the most significant prognostic factor in the multivariate analysis (P = <.002). After a median follow-up of 54.64 ± 33.80 months, the 5-year OS and DFS was 69.9% and 67.8%, respectively. Conclusion. In this largest cohort of childhood ALL from Pakistan, a high WBC count, malnutrition, delayed presentation, prior steroids use, intensive chemotherapy and poor response to the induction chemotherapy were associated with decreased OS and DFS rates.