The authors report the case of a three year old patient who presented with coeliac disease simulating an Hirschsprung's (constipation and megacolon). She underwent surgery many times and this was due to an initial diagnosis of aganglionic megacolon. Moreover the relationship between constipation and megacolon is discussed and some pathogenetic interpretations of megacolon, a common observation in patient with coeliac disease, are presented.