The stargazer rat displays abnormal behavior characterized by pronounced arching of the neck, head tics, and hyperactivity. Thus, stargazer rats may provide a behavioral model of Tourette syndrome (TS). The responsiveness of these rats to tactile startle stimuli was examined. Littermate controls showed significant prepulse inhibition and habituation over repeated startle sessions. Stargazer rats did not exhibit startle responses, even under conditions of haloperidol-induced reduction of abnormal behavior. These data disagreee with the hypothesis that stargazer rats would have increased responsiveness to startle stimuli due to their hyperactive dopamine systems. However, the reduction of head tics by haloperidol suggests stargazer rats are a model of TS. Thus, the mechanisms by which dopaminergic hyperactivity enhances eithe rhead tics or startle responsiveness appears distinct.