A simple, selective, rapid, precise and economical reverse phase HPLC method has been developed and validated for quantitative determination of Betamethasone in plasma. Paracetamol is used as an internal standard. The method was carried out with Analytical technologies Lts. Model no. 3000Series. The optimized chromatographic conditions were optimized using a mobile phase methanol: water in the ratio of 60:40 at flow rate 0.9ml/min. Stationary phase was used as Grace C18column (250mm x 4.6ID, partical size: 5 micron). Detection was carried out at 242nm.the method was developed and tested for linearity range of 10ng/ml to 160ng/ml. The developed method was validated in terms of selectivity, accuracy, precision, linearity and stability study. Proposed developed method can be used in bio analytical, bioequivalence & pharmacokinetic studies with desired precision and accuracy.