A simple and reliable reverse phase high performance liquid chromatographic (RP-HPLC) method has been developed for the quantification of p-Toluenesulfonic acid and Ethyl-p-Toluene sulfonate in Perindopril tert- Butylamine drug substance. The separation of p-Toluenesulfonic acid and Ethyl-p-Toluene sulfonate was achieved from the related impurities of the drug on an Inertsil ODS-3V (250 x 4.6mm) 5μm column. The gradient LC method employs solution A and solution B as mobile phase. The solution A contains 0.2% OPA and solution B contains Acetonitrile. The developed RP-HPLC has been subsequently validated to prove its performance characteristics by demonstrating specificity, limit of detection and limit of quantification, linearity, accuracy, precision and robustness. The drug substance was subjected to stability studies using optimized method condition to enhance low level of detection with minimum acquisition time indicating the accuracy of the optimized HPLC method by citing ICH guideline requirement.