An additional fatal case of Chédiak-Higashi's syndrome, occurring in the firstborn of a Canadian family, is reported. The parents were not related and the mother has subsequently given birth to a normal healthy child. The clinical features of the Canadian case were in all essential features similar to those reported by Chédiak and Higashi. The hematologic abnormalities were identical. In addition to findings referable to the blood dyscrasia, the post-mortem examination disclosed a peculiar type of "encephalomyelitis," probably secondary to a chronic degenerative process.