Background: Vitamin D is a fat-soluble vitamin found in blood, muscle, liver, fat, and other tissues. The regulation of calcium phosphorus balance and bone health are two of vitamin D's main roles. However, studies on both humans and animals suggest that vitamin D may play a part in the emergence of a number of endocrine disorders. Objective: The aim of the current work was to determine the baseline state of 25-hydroxyvitamin D levels in a sample of Egyptian schoolchildren and to assess how sun exposure affects vitamin D status. Subjects and methods: This cross-sectional study included a total of 50 apparently healthy schoolchildren, aged from 6 to 11 years, and performed at swimming pool center, in Benha, Egypt, between May 2018 and the end of September 2018 Vitamin D was measured twice, the first time in May, and the second time in September with good exposure to the sun three times/per week one hour before swimming. Results: Pre exposure mean vitamin D level was 26.9, while it was 27.1 after exposure, with no statistically significant difference between pre and post exposure levels. Vitamin D was sufficient in 40%, insufficient in 44%, deficient in 16%. No change was found in vitamin D status post exposure. Pre and post exposure vitamin D levels showed significant positive correlation with total calcium, ionized calcium, and significant negative correlation with body mass index (BMI). Darker skin, fast food, higher centile, BMI, formula feeding, lower sun exposure, activity level, total, ionized calcium was associated with risk of lower vitamin D status. Conclusion: It could be concluded that vitamin D deficiency and insufficiency are highly prevalent in sunny Egypt. To increase vitamin D status and reduce the risk of its deficiency, vitamin D supplementation, consumption of vitamin D-rich food, and the encouraging of outdoor activities should be considered. Our findings indicate that, despite receiving a lot of sun exposure, some children exhibit varied responses to ultraviolet Blight (UVB) light, which results in poor vitamin D status.