The present invention relates to a pharmaceutical composition comprising 2,3-dihydro-5,6-dimethoxy-2-[[1-(phenylmethyl)-4-piperidinyl]methyl]-1H-inden-1-one, herein after referred to as Donepezil, or a pharmaceutically acceptable salt thereof, for treating of Alzheimer's disease and senile dementia. The present invention also relates to a manufacturing process for the preparation of Donepezil tablets containing and retaining polymorphic Form I of Donepezil hydrochloride. This composition also discloses the use of the excipients that ensure adequate flowability of a dry blend as well as required content uniformity and drug release rate of the final product.