The invention relates to polymorphs of 4'-[2-n-propyl-4-methyl-6(1- methylbenzimidazol -2-yl) benzimidazol -1-ylmethyl] biphenyl-2-carboxylic acid (INN: telmisartan), and in particular the polymorphous form B of formula (I), characterized by an endothermic peak at 183 +/- 2 DEG C during thermal analysis by differential scanning calorimetry. The invention also relates to mixtures of said polymorphs, methods for producing telmisartan containing form B and to the use thereof in the preparation of a medicament.