Aim: In this study, we aimed to investigate the frequency of serum zinc deficiency in children with protein-energy malnutrition and to show the relationship between the degree of malnutrition and serum zinc level. Methods: Methods: This retrospective study was conducted at the Pediatric Gastroenterology, Hepatology, and Nutrition clinic in Selçuk University Hospital, and included 506 patients aged between 1 and 18 years who were diagnosed with protein-energy malnutrition according to the Waterlow classification. Results: The prevalence of serum zinc deficiency was 61.1% in patients with protein-energy malnutrition. The mean serum zinc levels of patients aged 1-5 were significantly lower than those of patients aged 5-12 and 12-18. There was no difference between malnutrition degrees calculated according to Waterlow criteria and mean serum zinc levels. Although the relationship between the degree of malnutrition calculated according to the BGA scale and the mean serum zinc level was not statistically significant, the mean decrease in serum zinc levels was remarkable in contrast to the increase in the level of malnutrition. Conclusion: It is important to routinely measure serum zinc levels in patients with PEM and to provide zinc supplementation if deficiency is detected.