OBJECTIVE: There is little evidence to support an increased risk of blood pressure (BP) elevation among elderly individuals receiving antihypertensive drug treatment. METHODS: To clarify the impact on BP level and residual cardiovascular risk in treated elderly individuals, we analysed individual participant data of 26 133 residents aged 60-89 years from seven Japanese general populations and cross-classified participants by age category, 60-74 (young-old) versus 75-89 years (old-old), and by usage of antihypertensive medication at baseline survey (1980-1995). RESULTS: During a median follow-up period of 12.7 years, 2451 cardiovascular deaths were observed. Multivariable-adjusted hazard ratios of cardiovascular mortality in treated participants compared with untreated participants were 1.30 [95% confidence intervals, 1.16-1.46) and 1.35 (95% confidence interval, 1.16-1.56) in young-old and old-old participants, respectively. Irrespective of antihypertensive medication, the risk increase of total cardiovascular and stroke mortality with elevation of BP was significant among young-old (P ≤ 0.0013), but not significant among old-old participants (P ≥ 0.061). CONCLUSION: Although impact on BP was more evident among young-old than old-old individuals, clinicians who prescribe antihypertensive medication to elderly patients should consider that such patients require further monitoring.