Of all known schizophrenics living in Nithsdale, south-west Scotland, 146 (88%) were examined for the presence of the three principal movement disorders secondary to antipsychotic medication, namely akathisia, tardive dyskinesia and Parkinsonism. Of these, 18% had akathisia, 5% pseudoakathisia, 29% tardive dyskinesia, 8% persistent tardive dyskinesia, and 27% Parkinsonism. No movement disorder was seen in 445, 36% had one and 20% had more than one movement disorder. Plasma neuroleptic levels at the time of clinical assessment were measured by the radioreceptor technique. Correlations between dose and plasma level were low; the ratio of mean plasma concentration to mean dose was greatest with fluphenazine decanoate and lowest for sulpiride. The concentration:dose ratio was higher in the elderly. There was no relationship between neuroleptic levels and akathisia, Parkinsonism or tardive dyskinesia. Additional psychotropic medication influenced neuroleptic levels. In 9% of patients receiving oral antipsychotic medication, no drug was detected in plasma.