A high-performance liquid chromatographic procedure for the determination of pirenzepine dihydrochloride as a bulk material and in its tablet dosage form (GastrozepinR) is presented. Normal phase liquid chromatography has been performed on a Micro-pack Si-10 column using ammonium hydroxide (28–30% NH3) in methanol (0.75: 99.25% v/v) as mobile phase at a flow rate of 2 ml/min. Clobazam has been used as internal standard with retention times of 1.9 and 2.8 minutes for clobazam and pirenzepine dihydrochloride, respectively at 254 nm. Analytical calibration yields a linear relationship between 5 and 25 μg/ml, with correlation coefficient of 0.999. Tablets each labelled to contain 25 mg pirenzepine dihydrochloride give mean percentage found of 99.98 ± 0.4. A plot of logarithm of concentration against time for a solution in 6 N hydrochloric acid gives a straight line with a slope of - 0.197 day−1. The proposed method is, therefore, a stability indicating method.