Abstract: The present invention relates to a process for preparing solid oral dosage forms e.g. tablets,capsules,coated tablets/capsules, etc. comprising as active ingredient 4-amino-1-hydroxybutylidene-1, 1-biphosphonic acid or one of its pharmaceutically acceptable salts (“Alendronic acid”). It comprises the free acid or one of its pharmaceutically acceptable salts. The process is characterized by granulating pharmaceutical carriers with an aqueous solution of Alendronic acid which is solubilized with the aid of alkaline hydroxides or alkaline salts. The oral dosage forms obtained by this process are less irritating to the digestive system than oral dosage forms obtained by conventional processes. The present invention also relates to tablets and to capsules prepared by said process.