Forty-six patients with tardive dyskinesia (TD) were studied to characterize the relationship between TD and parkinsonism. In two patients idiopathic parkinsonism (PD) preceded the use of neuroleptic drugs and in 15 patients TD was associated with drug-induced parkinsonism. Patients with TD alone were compared with patients who had the combination of TD and parkinsonism. Only age at onset of TD symptoms differentiated between the two groups (p less than 0.02); patients with associated parkinsonism had onset of TD later than patients with TD alone. Patients with PD may develop TD and the latter may be triggered by levodopa. When TD and parkinsonism are combined, the symptoms may be controlled by a careful use of dopamine depletors and levodopa.