The aluminum gallium nitride (AlGaN) alloy is uniquely suited for fabricating optoelectronic devices in the ultraviolet and visible bands of the spectrum. Its synthesis in a nanometer scale may potentially open the way for applications such as tunable optoelectronic devices. Presently, results concerning the synthesis and microstructural and optical characterization of nanometer-sized AlGaN imbedded in a poly-methylmethacrylate (PMMA) matrix are reported. Our optical measurement showed that the AlGaN/PMMA nanoparticle/polymer composite efficiently emits in the violet-blue region, while the microstructural characterization confirms the formation of defect-free zinc blende AlGaN nanoparticles. ©1997 American Institute of Physics.