The aetiology of Dupuytren's disease remains unknown, although hereditary and environmental influences have been implicated. Previous reports have suggested that identical twins will develop identical contractures. This paper reports two pairs of identical twins, in each of which only one twin has evidence of Dupuytren's disease. This demonstrates that an appropriate genetic background is inadequate of itself for the development of Dupuytren's disease without a suitable, and as yet unknown, environmental trigger.