We have measured acetylcholinesterase (AChE) and the butyrylcholinesterase (BChE) activities along strips of resected bowel specimens from thirteen children with Hirschsprung's disease. The AChE activity was variable along the length of the resected bowel, while the BChE activity remained constant. By contrast, the AChE/BChE ratio decreased rapidly to low levels when ganglion cells were present. We suggest that this ratio can be used to determine the normal segments of the bowel, to specify the anatomic forms (i.e. rectal or rectosigmoid) and may be useful in determining the anastomotic level.