Four enzymes were examined electrophoretically from each of seven stands of arctic umbilicate lichens in central Ellesmere Island. The species studied included Umbilicaria virginis Schaerer, which was prolifically apotheciate, and U. decussata (Vill.) Zahlbr. and U. hyperborea (Ach.) Hoffm., which were both sterile. Electrophoretic banding patterns were converted to presence/absence data reflecting the occurrence of electromorphs in each thallus, and enzyme polymorphism was assessed using three statistical methods, one based on frequency of individual enzyme forms, another on the number of banding patterns, and a third on the proportional representation of different band patterns within each collection site. Greater enzyme variability occurred in stands of apotheciate species than in stands of species which were asexual in the study area, suggesting that regular sexual reproduction contributes to greater diversity.