At this point, it is customary for all hands to gather round the old decision tree and whittle on a few algorithms. Because I have been chastened by occasional painful falls from slippery decision branches, however, I must make do with a short reprise. Some nodal points in analyzing vertical diplopia include: (1) evidence of central nervous system involvement; (2) pupillary sparing; and (3) the presence of proptosis of orbital congestion. As endlessly stated, premature closure of the differential diagnosis should be avoided and the tendency to diagnose partial third nerve palsy staunchly resisted. However, all of this will probably be of little comfort to you when you face your next lethargic patient who has small angle diplopia and speaks one of the obscure rural dialects of Freedonia.