Abstract: A pharmaceutical composition in the form of a tablet for controlled release of an active ingredient comprises cefaclor, cephalexin, or their pharmaceutically acceptable hydrates, salts, or esters as active ingredient, and a mixture of hydrophilic polymers of different viscosity grades selected from the group consisting of at least one hydroxypropyl methylcellulose and at least one hydroxypropylcellulose. The composition optionally also contains one or more of a water soluble or water dispersible diluent. The quantities of the hydrophilic polymers and water soluble or water dispersible diluent are such that the therapeutically effective active ingredient is released at a rate suitable for twice daily administration of the pharmaceutical composition to human subjects. The tablets may also be coated with a rapidly dissolving water soluble polymeric film coat.