Introduction: Undernutrition is an important prognostic factor in children with acute lymphoblastic leukaemia (ALL) and higher incidences of mortality are reported during induction remission in severely undernourished children. This study was conducted to assess the prevalence and implications of malnutrition among ALL children during induction therapy. Methods: All children ≤18 years diagnosed and treated for ALL at our institution, between June 2010 to July 2016 were included in this retrospective cohort study. Nutrition was assessed by body mass index-forage z-scores calculated using World Health Organization’s Anthro (<5 years) and Anthro-Plus Software (≥5 years). Children with a z-score of <-2 standard deviation (SD) were classified as undernourished. All events and outcomes were compared between undernourished and adequately nourished children. Results: A total of 72 children were included in this study. Nineteen (26.4%) were undernourished at the time of diagnosis. Twenty-eight (38.8%) children had significant weight loss. Sixty-seven of them attained remissions by the end of induction chemotherapy. Five children who died had significant weight loss. Children with significant weight loss during induction phase had a higher risk of developing complications such as febrile neutropenia, pneumonia, mucositis, and drug interruptions. Those with a deteriorating nutritional status had a higher chance of poor treatment outcome (p=0.05, CI=95%). Conclusion: It is important to assess and monitor the nutrition status of children and timely nutritional intervention is essential. A simple, cost effective nutritional intervention that will decrease morbidity and mortality associated with the disease must be devised.