BACKGROUND:
Vitamin D is essential for the maintenance of good health, and vitamin D deficiency has been reported from many countries including sunny ones. Due to the importance of vitamin D deficiency and its effects on children life quality, this study was conducted to evaluate the vitamin D status in healthy 6-year-old children in Isfahan city (2006).

METHODS:
513 healthy children were studied in this cross-sectional research. Blood was drawn for measuring biochemical parameters (serum PTH and 25-hydroxy vitamin D) and dietary vitamin D intake, duration of daily sunlight exposure, and percentage of body surface area exposed were measured using questionnaires.
Data was analyzed, using SPSS software, V13 (SPSS. Inc, Chicago IL.). The vitamin D serum levels less than 20 ng/ml and 10 ng/ml were defined as mild and severe vitamin D deficiency. ROC curve was utilized to obtain a cut-off point of vitamin D serum level in this study.

FINDINGS:
Using ROC curves, we defined the cut-off point of vitamin D deficiency in our population as 25-OHD level of 33 ng/ml .as the cut-off point of vitamin D deficiency in our population. Vitamin D serum level was < 20 ng/ml in 3% and < 33 ng/ml in 26% of cases. Duration of sunlight exposure (p<0.001, β =0.28) and daily intake of vitamin D had significant effects on serum level of vitamin D (p=0.002, β=0.13).

CONCLUSION:
In agreement with other researches, this study confirmed the high prevalence of vitamin D deficiency in children. Also it was found that improvements in duration of sunlight exposure and daily intake of vitamin D can prevent vitamin D deficiency in children.

KEY WORDS:
Vitamin D, 25-hydroxy vitamin D, vitamin D intake, preschool-aged children, sunlight, Iran.