Background In observational studies vitamin D was one of the factors associated with obesity.

Aims Determine the association between BMI and serum level of vit D in children from

Taleghani hospital as outpatient in Iran.

Design This was a cross-sectional observational study on 215 children, 2 to 7 years old referred to hospital in winter2013.

Methods and material In cross sectional study, it was measured weight, height, waist circumference with identical instrument, Also determined BMI, Vitamin D level was performed on ELISA method.

Statistical analysis Vitamin D levels less than 20 nmol/L was considered as deficiency, 20–30 nmol\L as inadequate and equal to or greater than 30 nmol\L as sufficient.it was applied t-test, ANOVA, Pearson correlation coefficient at the significant level of 0.05, data were analysed by SPSS.

Results 125 children were male and the rest were females 184 children had vitamin D deficiency and only 31 cases had adequate level. The prevalence of obesity and overweight was 27%, considering vitamin D status it was not significant. However, the linear relationship was between waist circumference and serum vitamin D (p < 0.01). The mean and standard deviation of vitamin D serum in girls and boys were 22/76 ± 11/62 and 23/46 ± 9/30 nmol/L and this difference was not significant.

Conclusions There was high prevalence of vit D deficiency in 2 to 7 years old. There was no significant relationship between BMI and vit D, but it was recorded in waist circumference with vitamin D level.