A 49 year-old women with no medical history suddenly presented bilateral striato-capsular infarct causing frontal-like behavioural disturbances associating inertia with loss of drive, interest and affect, and preservation of intellectual function ("athymhormic syndrome" or "loss of psychic self-activation"). Ischaemic lesions mainly affected right globus pallidus and left lentiform nucleus with no involvement of the caput of the nuclei caudati. Such changes were close to anoxic lesions known to cause the same symptomatology. Infarction was attributed to a Moyamoya disease on angiographic data. Bilateral involvement of basal ganglia, arterial borderzones or both, may explain the frequent occurrence of neuropsychological disturbances in Moyamoya disease.