Recently, ultrasonographic diagnosis of intussusception in children has become easier to perform. When intussusception is suspected clinically, ultrasonographic examination should be indicated routinely. In this paper, the ultrasonographic and abdominal X-ray findings of 39 intussusceptions in 35 children were compared with their reducibility by barium enema. We divided the characteristic ultrasonograms of intussusception (so-called pseudokidney sign) into four types: Type I: horseshoe high echo pattern, Type II: target pattern, Type III: one-sided high echo pattern, Type IV: irregular shape. In Type I cases, all 12 lesions were easily reduced by barium enema. In Type II cases, although the number of difficult cases increased, successful reduction was achieved in all of 16 lesions. Among 8 Type III lesions, three were easily reduced by barium enema, three were difficult and another two were impossible to reduce. Among 3 Type IV lesions, one was extremly difficult and another two were impossible to reduce. This suggests that barium enema reduction for intussusception of Type IV is extremly risky or impossible, thus mandating surgical intervention. These results suggest that ultrasonography is useful not only to diagnose intussusception in children, but also to predict its reducibility. When abdominal X-ray films show markedly gaseous distention of the small intestine (ileus), an attempt at barium enema reduction should not be made. However, most X-ray films show a normal gas pattern or localized distention of the small intestine. Although all 20 cases showing a normal gas pattern were reduced by barium enema, radiographically it is difficult to predict the reducibility of intussusception except for the ileus.