A family is described in which 5 (4 female and 1 male) of 8 siblings from one marriage developed a late onset cerebellar degeneration. Four of the 5 affected persons presented separately to different neurologists. Because the original enquiries into family history were negative, and because of the exclusion of other recognised causes for the clinical picture, a diagnosis of idiopathic chronic cerebellar degeneration was made for the individual patients. All patients experienced their first symptoms between the ages of 48 and 55 years, with a gradual unremitting deterioration from the onset. Cerebellar atrophy was confirmed on CT head scan in all cases. Clinically, apart from the cerebellar ataxia, there were no consistent signs of degeneration of any other central or peripheral nervous system pathway. Geographical factors severely limited family contact, and consequently none of those afflicted was aware of similarly affected relatives. Hence, this particular family illustrates the great importance of obtaining a detailed, accurate family history and of assiduous follow-up of the entire family. Only after many years did it become obvious that multiple members of the family were affected by a similar neurological problem.