This research describes the stability indicating RP-HPLC method in pharmaceutical tablet dosage forms for simultaneous estimation of Levocetirizine dihydrochloride (LEV) and Montelukast Sodium (MON). The proposed RP-HPLC method was developed using separation module Waters 2695 with PDA detector and chromatographic separation was performed at a flow rate of 1 mL / min using column Hypersil BDS C18 (250/4.6 mm, 5 μm) with a run time of 10 min. The mobile phase consisted of a 40:60% v / v Phosphate buffer and acetonitrile, pH with orthophosphoric acid was adjusted to 7.0 and the eluents were scanned at 230 nm using a PDA detector. Retention times for LEV and MON were 3.06 min, and 6.76 min, respectively. A linearity response was observed with a concentration range of 12.56-37.68 μg / mL for LEV and 23.78-71.20 μg / mL for MON. Limit of detection and limit of quantification for LEV are 0.079 µg/mL and 0.239 µg/mL and for MON are 0.156 µg/mL and 0.473 µg/mL, respectively. The stability indicating method was developed by subjecting the drugs to stress conditions such as acid, base hydrolysis, oxidation, neutral, photo-and thermal degradation, and the degraded products produced from the samples were successfully solved.