A collection of 70 Medicago introductions were field tested for resistance against potato leafhopper, Empoasca fabae (Harris), damage. All M. sativa L. ssp. sativa and most ssp. mixtures were susceptible. All ssp. falcata (L.) Arcangeli, one ssp. mixture sativa and caerulea (Lessing ex Ledebour) Schmalhausen, ssp. × varia (Martyn) Arcangeli and M. pironae Vis were resistant receiving one-half or less damage than the standard cultivars during four seasons of testing. Resistant introductions were slower in regrowth, attained less height, had smaller leaflets, thinner, tougher stems, and more prostrate growth than standard cultivars. Results suggest most observed resistance is due to avoidance of tough stems for oviposition.