We report here a case of a 20-year-old woman with facioscapulohumeral muscular dystrophy (FSHD). In this patient, the involvement of facial muscle had been present since early childhood, but obscured due to the complication of profound mental retardation. Epilepsy emerged at eight years of age. Symmetrical limb muscle weakness appeared at 15 years of age, which progressed such that she was wheelchair-bound at 18 years of age. An elevated serum creatine kinase, predominant involvement of hamstrings, scapular and abdominal muscles, as well as an impaired stapedial reflex at high tune, were compatible with the clinical features of FSHD. The diagnosis of 4q35-FSHD was confirmed by detection of a 10kb EcoRI fragment with a p13E-11 probe on a Southern blot. The intellectual disability in this patient was the most severe of all FSHD patients reported to date and has hindered a correct diagnosis. This entity should be included in the differential diagnoses for patients with muscular symptoms and accompanying mental retardation.