The behavioural and movement disorders reported in 240 patients described in the literature with lesions affecting the caudate nucleus, putamen and the globus pallidus (lentiform nucleus) have been analysed. Reports were classified into two groups: small or isolated lesions involving the said nuclei alone; and large lesions with additional involvement of the adjacent internal capsule and/or periventricular white matter. Amongst the 240 cases, dystonia was the most frequent movement disorder recorded (36%); chorea (8%) and parkinsonism (6%) or dystonia-parkinsonism (3%) were uncommon. The commonest behavioural disturbance was the syndrome of abulia (apathy with loss of initiative and of spontaneous thought and emotional responses) (13%); disinhibition was rare (4%). Confusion usually was associated with intracerebral haemorrhage and depression was a relatively non-specific finding. Aphasia was extremely rare with lesions confined to these basal ganglia structures. Lesions of the caudate nucleus rarely caused motor disorders but were more likely to cause behavioural problems. Chorea has been described in only 6% of those with caudate lesions, and dystonia in only 9%. The most significant behavioural disturbance described in 28% of those with caudate lesions was the syndrome of abulia, sometimes alternating with disinhibition (11%). Lesions of the lentiform nuclei rarely caused abulia (10%) and did not produce disinhibition, but they commonly caused dystonia (49%), particularly when the putamen was involved (63%). Bilateral lesions of the lentiform nuclei, either of the globus pallidus or of the putamen, caused parkinsonism (19%) or dystonia-parkinsonism (6%) infrequently. The prominence of the behavioural disturbance of abulia with caudate lesions emphasizes the more complex cognitive role of this basal ganglia structure. The frequent occurrence of dystonia and less commonly of parkinsonism with lentiform lesions emphasize the motor roles of putamen and globus pallidus.