A new sensitive, specific, linear, precise and accurate RP-HPLC method was developed and validated for estimation of Quetiapine fumarate in Bulk and Tablet dosage form. An isocratic, reversed phase HPLC method was developed. Shimadzu shim pack C18(150mm x 4.5µm, x 5µ) column. Shimadzu Prominence-I LC-2030C plus equipped with Auto sampler as the instrument model. Mobile phase consists of mixture of Acetonitrile: 0.1% Ortho phosphoric acid in Millipore water v/v: Methanol in the ratio (60:30:10 v/v) at a flow rate of 0.8mL /min with injection volume of 20µL. UV detection was performed at 252nm. The Linearity was established for Quetiapine fumarate in the range of 2-12µg/ml with correlation coefficient of 0.997. LOD and LOQ were found to be 1.053µg/ml and 1.161µg/ml respectively. Retention time of Quetiapine fumarate were found to be 3.4mins. % Recovery was found to be 98.99-100.5 and %RSD was found with in ± 2. The method has been validated according to ICH guidelines for linearity, precision, accuracy, robustness, ruggedness, LOD and LOQ. The developed validated method was successfully applied for reliable quantification of Quetiapine fumarate in bulk and pharmaceutical dosage form.