Currently several varieties of tomato, Lycopersicon esculentum have become commercially available for the control of several piercing-sucking pests. These cultivars contain the Mi gene, which has been shown to confer resistance to a nematode, aphid and whitefly. While host-plant resistance is used to control other piercing-sucking tomato pests, the resistance of the Mi tomato to the tomato psyllid has not been examined. The tomato psyllid, Bactericerca cockerelli (Sulc), is a serious pest of tomato in the western half of North America. The tomato psyllid injects a secretion while feeding during nymphal stages that initiates a cascade of physiological events in the plant called “psyllid yellows”. Although this pest has been studied for over 80 years, little is known of the plants molecular responses to the adult and immature feeding and secretions. Our objective was to assess the resistance of the Mi tomato to the tomato psyllid and determine the changes in plant RNA profiles in response to adult and nymph damage.