Background A significant public health issue, malnutrition affects 50 to 150 million children under the age of five globally. An increase in morbidity and mortality has been linked to malnutrition, a serious public health problem.

Aim: To determine whether malnourished children under the age of five with or without diarrhea have electrolyte disturbances in their serum.

Methodology: 100 malnourished children under the age of five were randomly selected from Liaquat University Hospital Jamshoro/Hyderabad. It took place between January 2019 and December 2020. They were malnourished in varying degrees, with or without diarrhea. Their histories, examinations, and measurements were used to divide them into two groups: 56 malnourished patients with diarrhea and 44 malnourished patients without diarrhea. In both groups, serum electrolytes were compared and data were analyzed in SPSS version 21.

Results: According to electrolyte findings, group A had more hyponatremia and hypokalemia than group B. respectively. 43 patients (79.6%) in group A had hyponatremia, but 36 in group B (78.2%). Hypokalemia affected 27 patients (50.0%) in group A, but 10 (21.7%) of those in group B (p-value 0.02).

Conclusion: Electrolyte changes were common in moderately and severely malnourished children, particularly those who presented with diarrhea. Morbidity and mortality can be reduced if these changes are detected in time.