The clinical features of 53 British-born patients with Gilles de la Tourette syndrome are described. The mean age at onset of body tics was seven years and for vocalisations 11 years. Coprolalia was present in 39%, copropraxia in 21%, echolalia in 46% and echopraxia in 21%. Complicated antics and mannerisms were also common, often involving the compulsive touching of objects or self-injurious behaviour. Forty-six per cent of cases had a family history of tics in a single close relative and in two individuals a further member of the family had Gilles de la Tourette syndrome. Focal dystonia was present in four patients who had never received neuroleptics drugs and chorea was seen in two other untreated patients. In three patients acoustic startle consistently induced brief eye blink followed by a whole body jerk or jump. Rapid repetitive movements of the hands increased the frequency and severity of tics in 13 patients, but the performance of mental arithmetic under time pressure had a much more unpredictable effect. Electroencephalographic abnormalities occurred in eight (13%) but no definite CT brain scan abnormalities were detected. The incidence of left handedness did not differ from that in the general population and no evidence to suggest organic impairment was found on neuropsychological testing. This study provides no support for the notion that Gilles de la Tourette syndrome is a degenerative disorder of the central nervous system but provides some evidence for heterogeneity.