||A simple method was developed and validated for the simultaneous estimation of Lamivudine and Tenofovir disoproxil fumarate in pharmaceutical dosage form. The method was based on RP-HPLC. Chromatographic separation was performed on Symmetry C18 (4.6 x 150mm, 5m, Make: Waters) or equivalent ,column using a mobile phase consisting of a mixture of KH2PO4 buffer (pH 2.5 with dilute ortho-phosphoric acid): Methanol: phosphate Buffer (700%v/v) in an isocratic mode. The following system conditions were maintained throughout development and validation i.e., flow rate 1.0 mL/min, column was maintained at room temperature and the detected by a UV-wave length at 260nm. The Lamivudine and Tinofovir were well resolved on the stationary phase and the retention times were 2.464 and 3.746 minutes respectively. The method was validated; both the drugs were shown to be linear over a range of 300 μg/mL. Precision Intermediate Precision/Ruggedness Accuracy linearity Limit of detection Limit of quantification Robustness was determined to validate the method.