A sensitive, selective and simple post-column detection method for the determination of propylthiouracil (PTU) based on its sensitizing induction on iodine-azide reaction and the combination technique of high-performance liquid chromatography has been presented. The analysis was conducted in the optimum conditions for iodine-azide detection system and HPLC separation. The linear range, the lower limit of detection and quantification for PTU in urine were established at the levels of 0.4-1.0 nmol/ml urine, 0.3 nmol/ml urine and 0.4 nmol/ml urine, respectively.