Background: Malnutrition in children < 5 years is a public health concern due to its associated high morbidity, mortality and serious long-term consequences. The World Health Organization (WHO) recommends 10 steps for the management of severe acute malnutrition (SAM) children which also involves correction of electrolyte disturbances. Treatment with diets having inadequate amounts of minerals like phosphate can result in refeeding syndrome and other abnormalities. We conducted the study among children with medically complicated SAM to evaluate their serum phosphate levels after receiving locally prepared therapeutic feeds and its associations of other factors. Methods:The study was conducted with 120 hospitalized SAM children aged 6 -59 months with presence of other illnesses. All children were managed according to the WHO protocol and facility-based management of SAM guidelines of the government of India. Basic demographic details of the child were recorded. Weight of the child was recorded daily, while length/height and mid-upper arm circumference (MUAC) were recorded weekly. We evaluated changes in serum phosphate levels at three time points: on admission, during transition and at discharge. Binary logistic regression analysis was conducted to assess the association of hypophosphatemia with several other indicators.Results: Mean serum phosphate was 4.38 ± 1.07, 4.48 ± 1.16 and 5.13 ± 1.10 mg/dL on admission, during transition and at discharge, re-spectively. Hypophosphatemia was present among 30 (25%) children on admission, 28 (23.3%) children during transition and 10 (8.3%) children at discharge, which showed a decrease in the prevalence of hypophosphatemia from admission to transition and discharge using the current treatment. The finding also showed positive and significant changes in serum phosphate levels among children who were admitted without edema compared to those admitted with edema. Binary logistic regression estimates showed that older children, children with lower WAZ, hypokalemia, hyponatremia and anemia had higher odds of hypophosphatemia. Male children had lower odds of hypophosphatemia. Conclusion:The nutritional therapy with locally prepared starter and catch-up diet was effective in normalizing hypophosphatemia in the majority of children treated. Serum potassium and serum sodium levels were significantly associated with serum phosphate, indicating the need for careful monitoring of serum phosphate in the presence of hypokalemia and hyponatremia among SAM children.