Background: This was a prospective observational study done to observe the effects of telmisartan on cognitive function in hypertensive dementia patients.Methods: The study included new diagnosed hypertensive and normotensive dementia patients. Patients comprised of four groups; hypertensive dementia patients taking telmisartan (group 1), hypertensive dementia patients taking donepezil and telmisartan (group 2), normotensive dementia patients taking donepezil (group 3) and normotensive dementia patients taking drugs which does not affect memory (group 4).Cognitive function of four groups were compared to each other at 4, 8 and 12 weeks.Results: In group 1, 2 and 3 mini-mental state examination (MMSE) scores has increased by 1.69, 16.81, and 13.28 percent and in group 4 there is decrease in MMSE score by 6.03 percent in 12 weeks.Conclusions: In this study we can conclude that telmisartan has dementia preventing propensity which is better than placebo but not as good as donepezil.