Congenital cerebellar atrophy associated with a non-progressive cerebellar syndrome and mild cognitive retardation is described in seven cases, four of them familial. Their occurrence is consistent with an autosomal recessive inheritance. Clinical and neuroimaging data seem to exclude supratentorial changes. Even though it is not possible to definitely rule out a possible role of the forebrain in determining the mental defect, the neuropsychological study supplies arguments stressing the relationship between cerebellar defect and cognitive development.