1. Three families with the characteristic changes of the nail-patella syndrome are reported. In addition to the well established bone and nail defects they had soft-tissue contractures, web formation around the elbows and muscular hypoplasias. The literature on soft-tissue changes is reviewed and their importance emphasised. 2. Asymmetrical joint development is considered to be a characteristic feature of the syndrome. 3. The incidence of renal disease in our families is recorded. 4. The literature on the basic defect is reviewed. The likelihood of a primary alteration in connective tissue chemistry is considered.