From forty years new knowledges about Hirschsprung's disease have dramatically transformed classical concepts of congenital megacolon. The author emphasizes successive steps of knowledges fron his personal experience of 500 patients observed at Pediatric Surgical Department, Hôpital des Enfants Malades, Paris, and own contribution at several research programs on this topic. They concern Radiology, Manometry, Histochemistry, Immunocytochemistry. Using technics of molecular biology, recent progress in knowledge of neural crest cells migration towards myenteric plexus, light etiopathogenesis of the disease. Several pathological associations suggest the genetic origin of the neuro transducers defect. Whatever be the scientific interest of it, clinical lethal risk of early enterocolitis remains a daily evidence. Simple routine precocious deflation of colonic hyperpression is still the most important message to be stressed.