Bismuth (0-20μgml - 1 ) can be determined spectrophotometrically at 485nm after its adsorptive extraction from dilute sulfuric acid solution as tetrabutylammonium tetraiodobismuthate(III) on microcrystalline benzophenone followed by dissolution of the solid phase in ethyl acetate. The effects of reaction conditions, diverse ions and masking studies are reported. The system has been applied to the determination of bismuth in pharmaceutical samples.