A simple, fast, sensitive method for the determination of preservatives (methyl parahydroxybenzoate, propyl parahydroxybenzoate) in the finished dosage form of sodium oxybutyrate syrup based on the simultaneous determination of preservatives using high performance liquid chromatography (HPLC) is proposed. The HPLC method was validated. The correlation coefficient of the linearity of the technique was 0.999 in the application range of 80–120 % of the normalized value. The calibration graph is linear in the region of 0.495–0.990 mg/ml of methyl 4-hydroxybenzoate and 0.165–0.330 mg/ml of propyl 4-hydroxybenzoate. It has been established that the analytical characteristics of the test procedure (selectivity, linearity, correctness, repeatability, reproducibility) satisfy the selected acceptance criteria.