The occurrence of a thalamic syndrome in a case of an old cerebral injury at birth and its surgical treatment by removal of a porencephalic cyst have not previously been described. Despite the absence of a pathologic study (as the patient is alive and well), the report of a single case seems desirable at this time because of its unique nature and relevance to the subject of thalamic dysfunction in general. In a recent discussion of porencephaly by Patten, Grant and Yaskin1there was no mention of thalamic involvement. Although thalamic dysfunction has been studied by various workers, there has been little agreement on the fundamental issues. It is hoped that the present case may help to clarify the situation. The thalamic syndrome, as described by Head and Holmes,2is characterized by the following features, the individual prominence of which may vary in the particular case: 1. Hemiplegia