Disorders of speech and other mental functions in eight patients with left thalamic hematoma were examined, both in their acute and chronic stage. The examinations in the acuts stage revealed a decrease of vigilance in 7 cases, fatiguability in 6 cases, a paucity of spontaneous speech in 6 cases and small vocal volume in 5 cases. In addition, 6 out of cases exhibited some speech disorders, inluding paraphasia, word-finding difficulties, circumlocution. The other two cases showed memory dis turbance and / or disorientation. Fluency, repetition and comprehension were well preserved in all cases. And, in the chronic stage, disor ders of speech and other mental functions almos disappeared in 7 cases out of the 8.     Those defects were not considered as being aphasia, but as a lack of activation of higher mental functions in the dominant hemisphere.