Rats bearing NMDA lesions of the lateral hypothalamus (LH) were tested for their reactions to alterations in the sensory (but not calorific) content of the diet (finickiness), to 24 h food or water deprivation, and to dehydrating injections of hypertonic saline and glucoprivic injections of 2-deoxy-D-glucose (2-DG). Lesioned rats lost weight following surgery but had no significant eating or drinking difficulties in the home cage. They were not finicky and responded normally to 24 h food or water deprivation. Responses to hypertonic saline and 2-DG challenges were significantly impaired. These data suggest a subtle motivational disorder following LH lesion, rather than motor or sensory impairment.