Background and Objectives: To determine the effect of oral nutritional supplements (ONS) on children with acute lymphoblastic leukaemia undergoing remission-induction chemotherapy. Methods and Study Design: We included 127 paediatric patients who were diagnosed with acute lymphoblastic leukaemia and undergoing remission-induction chemotherapy in the First Affiliated Hospital of Zhengzhou University. Children from two paediatric wards who met the inclusion criteria were enrolled. One ward was randomly chosen as the intervention group and the other ward as the control group. Children in the two groups were matched for age and sex. The ONS group was administered Peptamen® (n=60) and the control group was administered a low-fat diet (n=67). Results: The baseline information before treatment was not significantly different between groups (p＞0.05). In the control group, weight loss at the end of chemotherapy was significantly higher than that of ONS group (p＜0.05). The hemoglobin level and the concentrations of total protein, albumin, and pre-albumin were significantly higher in the ONS group than in the control group (p＜0.05 and p＜0.01, respectively). The incidences of hypoalbuminaemia, gastrointestinal complications, and infection were lower in the ONS group than in the control group (p＜0.05). The ONS group also used lower amount of albumin infusion, fewer blood-product infusion, and had lower hospital costs than the control group. Conclusions: During remission-induction chemotherapy, oral nutritional supplements can improve the nutritional status of children, reduce the incidence of complications, and decrease the costs of hospitalization.