Ag colloidal particles stabilized by poly (N,M-methylene bis-acrylamide N-aminoethyl piperazine) (MBA-AEPZ) were prepared. The Ag+ ion concentration and reaction temperature were studied on the size and size distribution of Ag colloidal particles, which were determined from the ultraviolet (UV) plasmon absorption band and transmission electron microscopic (TEM) analyses. The data show that poly(MBA-AEPZ) behaves like lower molecular mass stabilizers; some polymers surround the surface of the Ag colloidal particles and the particle size can be controlled by a change in the Ag+ ion concentration and reaction temperature. (c) 2006 Wiley Periodicals, Inc.