Cholecystokinin (CCK) is deeply involved in the control of learning and emotional behaviors. The authors characterize the behavioral properties of Otsuka Long Evans Tokushima Fatty (OLETF) rats, which lack the CCK-A receptor because of a genetic abnormality. In the Morris water-maze task, the OLETF rats showed an impaired spatial memory. In the inhibitory avoidance test, they showed facilitating response 24 h after training. Hypoalgesia was observed in a hot-plate test. In the elevated plus-maze and food neophobia test, OLETF rats showed an anxiety-like response. In addition, OLETF rats were hypoactive in the Morris water-maze and the elevated plus-maze. The results suggest that the OLETF rats showed a spatial memory deficit, hypoactivity and anxiety due, at least in part, to the lack of CCK-A receptors.