In this issue of Radiology, investigators from two countries in two separate studies report the colonic perforation rate at computed tomographic (CT) colonography on the basis of their experience (1,2). Although,the investigators in both studies conclude that CT colonography appears to be safer than optical colonoscopy, they nonetheless report a perforation rate at CT colonography I hat is substantially higher than that recently reported by the international Working Croup on Virtual Colonoscopy (3). Thus, it is essential to review these studies so that their findings are not considered to represent the actual risk for screening of healthy asymptomatic adults with CT colonography. There are several common features between these two studies that provide the necessary insight to place them in their proper context. Before discussing these specific studies, I would first like to share the findings of an even larger survey encompassing more than 20 000 studies with CT colonography that uncovered very different results.