Sclerotic skin change in systemic sclerosis (SSc) usually accompanies increased skin thickness. In order to quantify the cutaneous changes and to clarify the changes in the 'uninvolved' skin in systemic sclerosis (SSc), we measured the skin thickness on the chest, the forearms and the hands of 79 patients with SSc and 81 healthy controls with a B-mode ultrasound (30 MHz) apparatus. The thickness of the 'uninvolved', as well as the 'involved' skin in patients with SSc was significantly greater than that of healthy controls. Increased skin thickness on the forearms and/or the hands showed a 64.6% sensitivity and a 100% specificity for SSc. These results indicated that the skin which appears to be 'uninvolved' in patients with SSc is already pathologic, as shown by increased thickness. Moreover, measurement of skin thickness may be beneficial in the diagnosis of this disease at an early stage.