Vitamin D deficiency has been proposed as an associating factor with increased blood pressure. We studied the relationship between serum vitamin D and blood pressure in a large representative sample of Iranian population. In this cross-sectional study, based on the data of 2508 adults (aged between 20 and 70 years) from the Iran Multicenter Osteoporosis Study (IMOS), the association between serum vitamin D and blood pressure was investigated. There was a significant difference between mean (±SD) vitamin D levels of the individuals with stage I hypertension and that of the three other groups (Normal: 32.9 (±27.5); Prehypertension: 34.4 (±27.2); Stage-I: 38.7 (±29.2); Stage-II: 34.7 (±24.0) ng/ml; P<0.05. In multivariate regression models, the weak positive association of vitamin D and systolic blood pressure values disappeared after age and Body Mass Index (BMI) adjustment. We found a statistically positive but weak association between vitamin D serum concentration and systolic blood pressure. Considering the difference noted between our results and previous studies, further research is needed to assess the potential effect of ethnicity and genetic factors on these findings.