The study describes the stability indicating RP-HPLC method for simultaneous estimation of cilazapril and hydrochlorthiazide in pharmaceutical dosage form has been developed. The proposed RP-HPLC method was performed with reversed phase C18 column (Luna C18 column) equilibrated with mobile phase comprising of Methanol: Buffer (60:40, v/v, pH 4.0 adjusted by using 5% solution of orthophosphoric acid) was used. The flow rate was maintained at 1 mL/min. as it gave a good peak shape and resolution. A linearity response was observed in the concentration range of 0.5 - 40 µg/mL for cilazapril and 5 - 60 µg/mL for hydrochlorthiazide respectively. Limit of detection and limit of quantification for cilazapril are 0.17µg/Ml and 0.5 µg/mL and for hydrochlorthiazide are 1.3µg/Ml and 4.1 µg/mL, respectively. The recoveries found to be 97.67 % - 98.90% and 97.60%-99.06% for cilazapril and hydrochlorthiazide respectively. The stability indicating method was developed by subjecting the drugs to stress conditions such as acid and base hydrolysis, oxidation, and photo- and thermal degradation and the degraded products formed were resolved successfully from the samples. The result shows that the proposed method is suitable for the routine quality control analysis of simultaneous determination of cilazapril and hydrochlorthiazide in bulk and pharmaceutical dosage form.