Within three generations of one family four patients were found to have the carpal tunnel syndrome. In father and son, symptoms commenced in the first decade, and in both patients the median nerves were found to be constricted under the transverse carpal ligaments. The only other operative finding was considerably thickening of the transverse carpal ligaments in the father. Thickening of the transverse carpal ligaments is unusual in patients with the carpal tunnel syndrome but is a common finding in the relatively few patients with familial carpel tunnel syndrome so far described in the literature. It is suggested that thickening of the ligaments may constitute a familial disorder that can give rise to the carpal tunnel syndrome in childhood or later in life.