Lingual motricity was prospectively studied in 32 consecutive stroke patients with hemiparesis or hemiplegia involving the face. We excluded patients with vertebrobasilar infarcts, controlateral stroke, arteriovenous malformations, internal carotid artery dissection, severe aphasia or severe bucco-lingual apraxia. The study population consisted of 18 males and 14 females with a mean age of 64.2 years. Seventeen patients had a lesion located in the right hemisphere and 15 in the left one. The lesion was of ischemic origin in 19 patients and hemorrhagic in 13. Lingual motricity was studied at rest and at protraction. We recorded whether the following abnormalities were present: lingual deviation, limitation of protraction or lateral movements, atrophy, hypotonia and fasciculations. Sixteen patients had a deviation of the tongue at protraction. The other abnormalities were deviation of the tongue at rest, limitation of lateral movements at protraction, unilateral lingual hypotonia and limited protrusion. Of 16 patients with deviation of the tongue at protraction, 10 had no deviation at rest. Of the 6 remainders, 2 had deviation of the tongue towards the opposite side, at rest, and 4 towards the same side. Most patients with deviation of the tongue at protraction, had a lesion of the posterior limb of the internal capsule and of the posterior part of the lenticular nucleus. Most patients without lingual deviation, had a lesion of the capsule-lenticular region and of the superior portion of the internal capsule, just under the corona radiata.(ABSTRACT TRUNCATED AT 250 WORDS)