A reversed phase high-performance liquid chromatographic method was developed and validated for the quantitative determination of two antiviral drugs viz. lopinavir and ritonavir. Chromatography was carried out by gradient  technique on a reversed-phase C18 Column, Phenomenex (250 x 4.6 mm, 5 µ) with mobile phase mixture of Buffer: Acetonitrile (45:55 v/v) was used as a mobile phase and the pH was adjusted into 4.5 by using with O-phosphoric acid, at a flow rate of 1.2 ml/min. The UV range was detected at 240nm for lopinavir and ritonavir respectively. The different analytical performance parameters such as linearity, precision, accuracy, and specificity, limit of detection (LOD) and limit of quantification (LOQ) were determined according to International Conference on Harmonization ICH Q2B guidelines. The linearity of the calibration curves for each analyte in the desired concentration range is good (r2 >0.9). The recovery of the method was between 102.1% and 100.1% for lopinavir and ritonavir respectively. Hence the proposed method is highly sensitive, precise and accurate and it successfully applied for the reliable quantification of API content in the commercial formulations of lopinavir and ritonavir. Key words: Lopinavir, Ritonavir, UV spectrophotometry, RP-HPLC.