The radiographic files of 70 patients with Kienbock's disease were analyzed. Ulnar variance, carpal height and Kienbick stage were determined. A significant difference in ulnar variance was seen between early and late stages of the disease. In later stages there is a marked negative ulnar variance, not caused by bone apposition on the radius. We hypothesize that negative ulnar variance encourages further progression of the collapse of the lunate, while neutral or positive ulnar variance seems to protect the lunate against deformation.