We have studied 5 patients having a language disturbance associated with a left thalamic lesion documented by computerized tomography. These patients were submitted to a french adaptation of the Boston Diagnostic Aphasia Examination, originally designed by Goodglass and Kaplan. A quantitative analysis of these language disturbances has shown that they are characterized by reduction of fluency, resembling that of dynamic aphasia, with impaired volume, tone and articulation of speech. There is also a difficulty at finding word categories. Perseverations are frequent while paraphasias are scarce, being then mostly incoherences. Comprehension is impaired, but only at a complex level. Reading and writing are inconsistently affected. This symptom-complex is coherent enough from case to case to be considered as a recognizable type of aphasia, and specially since it is invariably associated with a left thalamic lesion.