CT scan and magnetic resonance imaging in patients with bilateral lesions of the lenticular nuclei, especially the pallidum, have demonstrated a relationship between these lesions and obsessive-compulsive behaviours. Typical behaviour may satisfy the DSM III criteria for obsessive-compulsive disorders, but in some patients signs are limited to elementary stereotyped movements or thoughts, either together or separately. The same patient may exhibit several kinds of behaviour. The range of disorders suggests that circuits running through the striatum and pallidum participate in regulatory and unification processes of sensori-motor and mental systems. Neuropsychological and metabolic tests suggest that frontal circuits involving the pallidum are especially important in this process. Similar disorders may be observed in patients with frontal or bilateral lesions of the caudate. Obsessive-compulsive behaviour is often associated with a loss of psychic self-activation, but there are exceptions. This evidence suggests a similarity between obsessions related to demonstrated lesions of the basal ganglia and other diseases displaying obsessive-compulsive behaviour, including Gilles de la Tourette disease and the former obsessive neurosis, currently termed obsessive-compulsive trouble. As after von Economo encephalitis, these pathological and clinical features should be considered in the current interpretation of the mechanisms of obsession-compulsion. It appears to be easier to apply Charcot's intuitions about neuroses to obsessive-compulsive behaviour than to hysteria.