The hypothesis that the caudate nucleus is involved in the pathophysiology of tardive dyskinesia (TD) in schizophrenia was investigated by examining motor procedural learning on the pursuit rotor task and basal ganglia T2 relaxation times (T2) determined using magnetic resonance imaging (MRI). Increased severity of TD was associated with shortened caudate T2 and decreased motor learning. Motor-learning scores of schizophrenic patients with and without TD did not differ significantly from those of normal control subjects, but motor learning in the schizophrenic patients correlated with caudate T2. The results suggest that a corticocaudate system subserves motor procedural learning and provide converging evidence from neuropsychological and MRI measures suggesting caudate involvement in TD.