The diffraction efficiency and morphology of the transmission modes of holographic polymer dispersed liquid crystals were studied with respect to the molecular structure of poly(urethane acrylate) (PUA), the film (polymer/liquid crystal) and resin (oligomer/monomer) compositions, and the cell thickness. PUA, based on N-vinylpyrrolidone and ethyl hexyl acrylate, with low-molecular-weight poly(propylene glycol) at a low oligomer content, showed high diffraction efficiency. The results were interpreted in terms of the monomer reactivity and polymer elasticity. (C) 2004 Wiley Periodicals, Inc.