1 . A classification of Madelung's deformity on an etiological basis is suggested.

2. Seven patients with "idiopathic" Madelung's deformity and one occurring in association with Turner's syndrome are discussed.

3. Cytogenetic studies of five patients are recorded and their significance discussed.

4. Arthrodesis of the radio-carpal joint by the "wedge" technique is preferred for those patients whose symptoms warrant treatment.