A simple, rapid and efficient quantitative method has been achieved for the determination of terfenadine powder and its tablet form (Triludan)®. The method is based on comparison between the integration value of the singlet signal of the t-butyl protons, or the multiplet signal of the aromatic protons of terfenadine against the singlet singnal of the unsaturated residue of (an internal standard) maleic acid protons. The procedure as well as the results of the proposed method are accurate, precise and reproducible.