Ritonavir was originally developed as an inhibitor of HIV protease. It is one of the most complex inhibitors. It is now rarely used for its own antiviral activity, but remains widely used as a booster of other protease inhibitors. cytochrome P450-3A4 (CYP3A4). The drug's molecular structure inhibits CYP3A4, so a low dose can be used to enhance other protease inhibitors. The chromatographic conditions comprise of a column: Zorbax Bonus RP 18, 4.6x100mm, 3.5μ. A mixture of 0.01M Potassium dihydrogen phosphate buffer (pH 6.8), Acetonitrile in the ratio of 50:50 was used as Mobile phase. Quantitation was achieved by UV detection at 239 nm. A linear response (r2 - 0.999) was observed in the range of 200 to 800ppm (from about 40% to 160%of target concentration) for Ritonavir. The method was validated for Accuracy, Precision, Linearity, Specificity, robustness LOD,LOQ and stability are within the ICH specifications. The proposed method has been used to estimate the Ritonavir. It is also desirable to have less run time; Henceforth the analysis of assay sample will become fast and reliable. The method was validated to meet requirements of global regulatory filling.