In a review of the records of 169 patients having idiopathic carpal tunnel syndrome (CTS) documented by electrodiagnostic studies, CTS was found to occur significantly more frequently in the dominant hand of both right- and left-handed persons. The clinical implications of these findings are discussed, particularly as they relate to the role of repetitive hand activities in the etiology of CTS, and it is concluded that the increased daily activity of the dominant hand is a contributing factor in the development of CTS.