A simple and sensitive visible spectrophotometric method is described for the determination of Quetiapine fumarate in bulk and pharmaceutical preparations based on the formation of light green colored molecular complex with sodium nitroprusside in presence of hydroxyl amine under alkaline conditions and exhibiting λmax at 401 nm. The Regression analysis of Beer’s Law plot showed good correlation in a general concentration range of 2-10µg/ml with correlation coefficient (r2 = 0.996). The proposed method is validated with respect to accuracy, precision, linearity and limit of detection. The suggested procedure is successfully applied to the determination of the drug in pharmaceutical preparation, with high percentage of recovery, good accuracy and precision. The results of analysis have been validated statistically by repeatability and recovery studies. The results are found satisfactory and reproducible. The method is applied successfully for the estimation Quetiapine fumarate in tablet form without the interference of excipients.