The prevalence of overweight (body mass index (BMI)=25.0-29.9 kg m(-)(2)) and obesity (⩾30.0 kg m(-)(2)) has been increasing over the last several decades in Japan. We examined trends of the impact of overweight and obesity on hypertension (systolic/diastolic blood pressure ⩾140/90 mm Hg or antihypertensive drugs use) using four national surveys in Japan, from which the participants were randomly sampled from the entire population. Study participants aged 30-79 years were selected for each survey (10 370 in 1980, 8005 in 1990, 5327 in 2000 and 2547 in 2010). The results showed that the impact of overweight and obesity on hypertension had increased significantly (P=0.040 and 0.006 in men and women, respectively). From 1980 to 2010, the multivariable-adjusted odds ratios for hypertension, comparing overweight and obesity with normal weight (BMI =18.5-24.9 kg m(-)(2)), went from 1.94 (95% confidence intervals: 1.64, 2.28) to 2.82 (2.07, 3.83) in men, and from 2.37 (2.05, 2.73) to 3.48 (2.57, 4.72) in women. Most of the association was observed in overweight participants, as only 3% of the Japanese were obese. In addition to the relationship between excessive BMI and other adverse health conditions, the rise in the association with hypertension increases the urgency in addressing weight control. We need to address the overweight and obesity epidemic.