Two siblings with marked subcutaneous tissue atrophy, delayed dentition and a degenerative neurological condition characterised by nystagmus, ataxia and spasticity are described. Myelin was almost totally absent on the magnetic resonance image brain scan performed on one sibling. There was no history of photosensitivity and ultraviolet irradiation of cultured fibroblasts did not inhibit RNA synthesis. We believe that these children have a previously undescribed syndrome, which, although clinically similar to Cockayne syndrome, is readily distinguished from it.