Various populations presumed to be potato leafhopper,Empoasca fabae(Harris), were collected from various host plants and locations, and then e1ectrophoretically assayed for 12 enzyme loci. There was no evidence of genetic differentiation between populations. Small populations ofE. kraemeri,E. erigeron, andE.compareperlongawere assayed.E. kraemeriis a cryptic member of the fabae complex, and may occur together withE. fabae. Diagnostic alleles were found to distinguish betweenE. fabaeand the 3 otherEmpoascaspecies.