Body mass index (BMI) and hypertension have been found to be associated in most studies of diverse populations; however, little information is available on whether the positive relationship is consistent among individuals at work sites. A work site-based screening was performed in 30 682 employees with a mean age of 40.3 years. In crude models, higher BMI quartiles above the lowest quartiles (BMI < 20.6 kg/m2) were associated with progressively higher odds ratio (OR) of hypertension with an OR of 2.80 (95% confidence interval [CI]: 2.67-2.93) for the top quartile (BMI ≥ 24.6 kg/m2). Similar trends were found in fully adjusted models. Moreover, a 1-standard deviation (SD) increase in BMI was associated with a 42% significantly higher (95% CI 38-46) risk of hypertension after adjusting for other factors. Concordant relationships were revealed in all evaluated subgroups, even among those without traditional cardiovascular risk factors.