Gold nanoparticles were generated by ultraviolet irradiation of Langmuir-Blodgett (LB) films of octadecylamine (ODA), 4-hexacylaniline (HDA), and benzyldimethylstearylammonium chloride monohydrate (BDSAC) deposited from aqueous HAuCl4 subphases. Ln contrast, no gold crystals were observed in irradiated LB films prepared from monolayers of dipalmitoyl-DL-alpha-phosphatidyl-L-serine (DPPS) and dipalmitoyl-L-alpha-phosphatidylcholine (DPPC). X-Bay photoelectron spectroscopy, W-visible absorption spectroscopy, atomic force microscopy, and transmission electron microscopy measurements indicated the marked influence of the surfactants used to prepare the LB matrix on the shape of the gold particles. Particles formed in ODA and BDSAC LB films were grown with well-defined crystal faces, while particles generated in HDA LE films were irregular in shape.