The radiological findings pathognomonic of Hirschsprung's disease have been known for quite a long time. However, in addition to those diseases characterized by rectum or rectum-sigmoid aganglionosis (as in the classic form of Hirschsprung's disease), in pediatric pathology of surgical interest severe affections exist characterized by aganglionosis extending from the rectum to the entire colon, and exceptionally as far as the small bowel (ultra-long Hirschsprung's disease). The authors report on the results they obtained in radiological studies of 6 cases of total colonic aganglionosis by means of the current radiological procedures, i.e. plain abdominal films and barium enema. As for total colonic aganglionosis, no diagnostic radiological parameters have been assessed yet. The authors compare their results with those taken from international literature: microcolon with reflux into mega-ileum (2 out of 6 cases) appears to be the most suggestive X-ray finding for total colonic aganglionosis. Finally, the role is discussed of radiological studies in the diagnostic approach to total colonic aganglionosis. The authors conclude that, even though radiological investigations are indispensable, they are often not conclusive. Therefore, an accurate evaluation of the proximal extension of aganglionosis can be made only at surgery.