A 7-year-old boy with hereditary recurrent brachial neuropathy is described and the disease is traced through three generations. The disease is thought to be transmitted by an autosomal dominant gene. There is a wide spectrum of severity of attacks which have a tendency to recur at long intervals to appear during pregnancy or parturition. A troublesome but generally benign course can be predicted. There is no evidence at this time to believe that treatment other than supportive care has any real value.