The clinical diseases of ulcerative colitis (UC) and Crohn's disease (CD) w
ere defined by 1932-1933. After that, the major conceptual developments wer
e the recognition that regional enteritis could clearly involve the colon,
and that cancer and toxic megacolon could occur in both CD and UC. In the l
ast half of the 20th century the main thrust of gastroenterology at The Mou
nt Sinai Hospital has been in inflammatory bowel disease (IBD), with contri
butions to extra-intestinal manifestations, measurement of clinical activit
y in CD, the natural history of the placebo arm of controlled trials, compl
ications and therapy with corticosteroids, 5-ASA, 6-mercaptopurine, immunom
odulators and cyclosporine. Actuarial life tables were introduced for posto
perative recurrence and re-operation rates, as well as for quality of life
analysis. Two forms of CD were defined, perforating and non-perforating, an
d the role of the fecal stream was explored in light of the higher risk of
recurrence after operations with anastomosis as compared with ileocolostomy
.