• A 46-year-old man, the son of normal nonconsanguinous parents, had a rare progressive neurological illness that began in midlife and was characterized by seizures, buccolingual dyskinesia, orofacial tics, choreiform movements, areflexia, and neurogenic muscle atrophy. Acanthocytosis was present. The serum creatine kinase level was elevated and normobetalpoproteinemia was noted. A brother had a similar disorder. These clinical and laboratory characteristics are consistent with those of previously reported cases of neuroacanthocytosis, ie, familial amyotrophic chorea with acanthocytosis (FACWA). Features not previously reported in cases of FACWA and noted in our index patient are as follows: (1) an increased level of free sialic acid was detected in the serum; (2) haloperidol administered in high doses decreased the orofacial tics; (3) absence of the McLeod blood group phenotype was noted; and (4) Hispanic-Puerto Rican ancestry was documented.