Background: Skin mechanics may be affected by several dermatological and systemic conditions. The skin can act as a marker of generalized disease. Osteogenesis imperfecta (OI) is a heritable disorder characterized by fragile bones caused by a generalized disorder of collagen. The dermis has a relative increase of argyrophil and elastic fibers and a deficiency of adult collagen. The collagen defect is well described, but functional changes in tissue mechanics have not been studied in the skin. The functional changes may reflect general changes and may give insight into the pathogenesis of clinical problems in these patients. Objective: To examine skin mechanics (elasticity, distensibility, and hysteresis) in patients with OI. Methods: Ten patients with OI (mean ± SD age, 45.9 ± 11.5 years) and 24 age-matched control subjects (mean ± SD age, 43.3 ± 13.8 years) were studied. The suction cup technique was used (Dermaflex; Cortex Technology, Hadsund, Denmark). Results: Significant differences between the patients and controls were found in all measurements (P<.002). Skin elasticity was decreased in patients vs controls (55.5% [range, 50.9%-60.1%] vs 73.8% [range, 70.3%-77.2%]). Similarly, distensibility was decreased (2.10 mm [range, 1.85-2.35 mm] vs. 2.50 mm [range, 2.37-2.63 mm]), as was hysteresis (0.19 mm [range, 0.15-0.23 mm] vs 0.28 mm [range, 0.27-0.30 mm]). Conclusions: The skin of patients with OI is more stiff and less elastic than normal skin. It is speculated that similar differences may be found in other tissues in patients with OI. The results potentially offer a quantitative standardized measure of OI, which may further our understanding of the underlying physical problems of these patients, provide better case definitions, and assist in predicting the prognosis of patients with OI.