A serious limitation in the 3D reconstruction of aperiodic objects in the electron microscope is imposed by the difficulty in assigning the correct relative orientation to a population of molecules which may present themselves in any number of positions on the substrate. Additionally, some orientations may be found far more frequently than others. The hemoglobin of Lumbricus terrestris presents itself in only three or four easily recognizable positions in the EM. We have recently examined the possibility of inexact 3D reconstruction from a limited number of 2D projections and would like to apply this technique to this molecule using only the three most frequently found orientations (a ‘top’, ‘side’, and 45° diagonal) whose positions relative to one another can be interpreted with reasonable confidence.