A simple, fast and precise reverse phase high performance liquid chromatographic method was developed for the estimation of Fluoxetine hydrochloride in oral solution with its major excipient benzoic acid. The chromatographic separation was achieved on Zorbax eclipse plus-C8 (250x4.6) mm; 5μm column with an isocratic mixture of diethyl amine buffer (pH 3.5) adjusted with orthophosphoric acid: acetonitrile in the ratio of 55:45 v/v, respectively. The mobile phase was kept at a flow rate of 1ml/min with injection volume of 20μl and wavelength of detection 227nm at room temperature. The retention times for Fluoxetine hydrochloride and Benzoic acid was found to be 3.417±0.1min and 2.919±0.1 min, respectively. The linearity was obtained in the range of 40-200μg/ml for Fluoxetine and 5-25μg/ml for benzoic acid with correlation coefficient 0.999 for both. On carrying out degradation studies it was found that degradation products did not interfere with the detection of Fluoxetine and benzoic acid. The proposed method was found to be linear, accurate, precise, stable, robust and specific and was successfully applied for the determination of investigated drug with an excipient in oral solution.