The invention relates to a crystalline sodium salt of 4'-[2-n-propyl-4-methyl-6-(1-methylbenzimidazol-2-yl)benzimidazol-1-ylmethyl]biphenyl-2-carboxylic acid (INN: Telmisartan), to a method for the production thereof, and to the use of the same for producing a pharmaceutical having an angiotensin II antagonistic action.