Abstract: A simple, sensitive, and easy spectrophotometric method has been suggested for the determination of trifluoperazine-HCl. The developed method is based on the oxidation of trifluoperazine-HCl (TFPH) with an excess of N-bromosuccinimide [NBS] and then the unreacted NBS used in bleaching the colour of Bougainville [BgVa], which is extracted from Bougainville flowers collected from Mosul city. All factors that affected the two main reactions have been studied, including the type and amount of acid used in the first reaction (oxidation of trifluoperazine-HCl), the amount of Bougainville, the medium of reactions, and the times required for completing both oxidation and bleaching the colour of BgVa. The optimum conditions have been recommended. The present assay obeyed Beer's law (R2 = 0.9991) over the range of trifluoperazine-HCl concentrations from 5 to 75 g/ ml. The value of molar absorptivity is found to be 4.22x104 L/mol.cm, and Sandell's index value is 0.0113 g/cm2. The values of molar absorptivity and Sandell's index indicated that the suggested method has good sensitivity towards the compound under investigation, Trifluoperazine Hcl, with no interference from additives. The present mothed was applied successfully to the assay of Trifluoperazine HCl in (Tablet).