Aim of this study was to determine whether pancreatic size is altered in patients suffering from type I diabetes mellitus. Twenty-five diabetics (14 males and 11 females) and twenty-five healthy controls entered the study. All patients and controls were scanned by the same operator with the same US equipment after overnight fasting. The longitudinal and antero-posterior diameters of the head, body and tail and the transverse diameter of the head as well as the total area of the gland were measured through longitudinal and axial scans. The two groups were homogeneous relative to age, sex, distribution, height, weight and body mass index. All measured diameters as well as the total area of the gland were significantly smaller in diabetic patients than in controls (1-way ANOVA: p less than 0.001). These results may open new perspectives to US identification of possible changes in pancreatic size by a new US study including high-risk subjects without clinical signs.