Introduction: Vitamin D is essential for the healthy development and maintenance of bones, particularly in childhood and adolescence. We aimed to figure out the vitamin D concentrations among children who were 4 to 15 years and came to health check-up clinics of a private hospital in Yangon. Methods: This is a retrospective record review study over 1 year which included a total of 99 well children aged 4 to15 years. We collected demographic and clinical details as well as blood samples including (25 (OH) D and alkaline phosphatase. For statistical analysis, we applied IBM SPSS 25.0. Results: Among 99 participants, 43 (43.4%) were found to have vitamin D deficiency. The average serum 25 (OH) D level among all subjects was 21.77±7.03 ng/mL, while those with deficiency had an average level of 15.53±3.32 ng/mL. Notably, a higher percentage of obese children, 10 out of 16 (62.5%) were affected with vitamin D deficiency. There was a statistically significant age difference between the vitamin D deficient group (mean age 10.07±3.16 years) and their sufficient counterparts (mean age 7.70±2.71 years). Conclusions: A significant incidence of vitamin D deficiency was detected among healthy children. It appears to escalate with age, implying an inverse relationship between age and vitamin D levels. The association between low serum 25 (OH) D and obesity in children underscores the significance of dietary pattern, lifestyle modification, and sunlight exposure in attaining optimal vitamin D levels. These measures may lessen the risk of multiple disease states related to low vitamin D.