A centre of genetic diversity for white spruce,Picea glauca(Moench) Voss, is suspected in and around a refugial region in the Yukon Territory. Seed from the refugium (30 samples), a neighbouring region (42 samples) and from southern Ontario (50 samples) was examined for isoenzymes of formic (FDH), glutamic (GDH), and lactic (LDH) dehydrogenases and cationic peroxidases (CP). FDH patterns were uniform. There were three GDH bands which appeared in five patterns. Eleven isoenzymes of LDH were detected in 21 patterns. There were 25 CP bands and the pattern from each collection (containing 7–13 bands) was unique.The results from GDH, LDH, and CP analyses revealed differences between seed from the refugium and the adjoining regions. The patterns for LDH supported the hypothesis that the refugium was a centre of diversity but the GDH and CP patterns were more diverse outside the refugium. The LDH and CP analyses showed that the genetic resources of the two regions in the Yukon were more diverse than those in southern Ontario. Analysis of divergence showed that these differences were significant at the 1% level of probability.