A simple and rapid spectrophotometric method was developed for determination of buspirone HCl and doxazosin mesylate in bulk and pharmaceutical formulations. In this paper silver nanoparticles (Ag-NPs) were prepared chemically using sodium citrate as reducing and stabilising agent. Silver nanoparticles showed an absorption band at 420 nm. Aggregation of citrate stabilised silver nanoparticles (Ag NPs) were used for quantitative determination of the studied drugs with formation of a new red shifted band at 545, 690 nm for buspirone HCl and doxazosin mesylate respectively. Different experimental factors were optimised and the calibration curves were linear with concentrations of (0.10-0.60 μg/mL), (5.0-14.0 μg/mL) for buspirone HCl and doxazosin mesylate respectively. Validation of the analytical performance of the method was carefully investigated, and the results were satisfactory.