Cerebellar atrophy is often discovered at computerized tomography or MRI of the brain, but its exact cause is frequently difficult to determine. Alcoholism is the predominant factor, but numerous other diseases may also be considered. The diseases fall into two main categories: primary cerebellar degeneration with, in particular, olivo-ponto-cerebellar atrophy, and acquired atrophy which may be of paraneoplastic or endocrine origin or caused by toxic agents other than alcohol. In this review paper the stress is placed on the clinical, paraclinical and histological distinctive features of the different types of cerebellar atrophy. The modalities of onset and the course of these lesions are of particular importance. The authors propose a practical aid to the diagnosis in the form of a deliberately simplified diagram.