The shape-controlled synthesis of silver nanostructures (NSs) via sonoelectrochemistry has been investigated in aqueous solution of AgClO4 with the assistance of poly(N-vinylpyrrolidone) (PVP). The morphology of silver NSs depends strongly on the current density U) and the molar ratio (R) of PVP monomer to Ag+. By controlling reaction conditions, not only zero-dimensional silver nanoparticles (NPs) of spherical and oval shapes, but also 3D silver NSs composed of dendritic rod, dendritic sheet and flower-like dendrites (consisting of staggered nanosheets) were successfully prepared. We discuss the growth process as being mainly dependent on the adjustable driving force of electroreduction while being modulated by PVP that contributes mainly to the finer structure in the shape-controlled synthesis. (C) 2009 Elsevier B.V. All rights reserved.