Abstract: AIM To investigate the impact of different body mass indexes on progression to hypertension in non-hypertensive population. METHODS Subjects who participated in annual physical examinations and completed a minimum of 2 times were selected and they were divided into low weight group (BMI<18.5), normal weight group (18.5≤BMI<24), overweight group (24≤BMI<28) and obesity group (BMI≥28), according to baseline BMI. Clinical features were evaluated and incidence of hypertension was compared among four groups. According to different blood pressures at baseline, the subjects were divided into normal blood pressure group and high-normal blood pressure group. Multivariate Cox regression was used to analyze the effect of BMI at different blood pressure at baseline on the progression of hypertension. RESULTS 23 665 non-hypertensive subjects at baseline were enrolled.A total of 2 502 subjects developed hypertension after a mean follow-up of 3.6 years.The incidence of hypertension increased from low weight group to obesity group and were 2.80%, 6.41%, 17.88%, 27.84% in the low weight group, normal weight group, overweight group, and obesity group, respectively. Multivariate Cox regression analysis showed that the risk of hypertension increased from the normal weight group to the obesity group after adjusted for other confounding factors. The risk of hypertension in the overweight group and the obesity group were 1.22 times and 1.35 times higher than the normal weight group. This trend of increasing risk of hypertension from normal weight group to obesity group existed both in the normal group and the high normal group. CONCLUSION The incidence and risk of hypertension increase with increment of baseline body mass index.