A simple, selective, accurate reverse phase - high Performance Liquid Chromatographic (RPHPLC) method was developed and validated for the analysis of Lopinavir in bulk drug. Chromatographic separation achieved isocratically on a C18 column (Use Symmetry C18, 150 X 4.6mm, 5μ) utilizing a mobile phase of Acetonitrile: Methanol: Phosphate buffer (50:30:20v/v/v, pH 3) at a flow rate of 1.0ml/m with UV detection at 210nm. The retention time was 7.2667. The method is accurate (97.78-100.56%), precise (the % relative standard deviations of intra and inter-day were 0.172 and 0.199 respectively) and linear within range 1-150μg/ml (R2=0.999) concentration and was successfully used in monitoring left over drug. The limit of detection and limit of quantification for Lopinavir drug was found to be 0.01μg/ml and 0.03μg/ml.