A fast and sensitive method of high-performance liquid chromatography (HPLC) for determination of acetylsalicylic acid (ASA) and products of salicylic acid (SA) hydrolysis in tablets has been elaborated. Extraction was done with the mixture of methanol: formic acid (98:2 v/v) and separation of the components was achieved by using the colon of Ultropac Lichrosorb RP-18, 10 um, 4 cm x 250 mm and diode array detector. The mobile phase of methanol:water: :mol/1 H3PO4 (60:35:5) v/v, pP = 2.6 and safe flow of 1 ml/min were used. Follow up of chromatographic separation of ASA, SA and internal standard beta-naphtole (ITS) was performed at the wave length of 290 microns. The threshold of ASA was 0.5 mg/ml and of SA 0.0025 mg/ml.