Two exotic species of Xyleborus (Coleoptera: Scolytidae) of Asian origin have recently been detected in the United States. Xyleborus pelliculosus Eichhoff has been collected in Pennsylvania and Maryland, and X. atratus Eichhoff from Tennessee, Georgia, Maryland, Virginia, and West Virginia. Descriptions of both species and a revised, illustrated key to members of the genus Xyleborus in eastern North America are presented. An explanation is proposed for the large numbers of recent introductions of exotic ambrosia beetles from eastern Asia into eastern North America.