Six different sets of coordinates have been recently published for bacteriorhodopsin, with reported resolutions ranging from 3.5 A to 2. 3 A. Three of these are the result of electron crystallographic investigations of two-dimensional crystals of bacteriorhodopsin, whereas the others are from X-ray crystallographic studies of three-dimensional crystals of bacteriorhodopsin. How similar are these models? Are the structure determinations using X-ray diffraction data more accurate than those determined by electron crystallography? Is any one of these coordinate sets closer to the 'real' structure of bacteriorhodopsin than the others? Does the availability of newer models bring us closer to understanding how bacteriorhodopsin really works? These questions, as well as some related issues, are currently being explored.