Bacteriorhodopsin (bR) is a protein with a molecular weight of 26 000 found in the plasma membrane of Halobacterium sarinarium. The versatile optical functions of bR, especially when it is organized in oriented membranes, make it a material of potential interest for the development of intelligent optoelectronic devices. Recent progress in the orientation of the bR moieties and in the application of the oriented structures in devices is reviewed.