The survival rate in 709 patients with chronic inflammatory bowel disease (CIBD) was calculated by the log rank test. There were 297 patients with Crohn's disease (CD) and 412 patients with ulcerative colitis (UC). In both diseases there was a survival rate of about 94% in the first year of observation against an expected rate of 99.5% in a general population matched for sex and age. This was because a large number of patients were severely ill at their first admission and required immediate or early surgery. During the subsequent 11 years the death rate in CIBD was higher (two to three times) than in the general population. After 12 years the survival rate was about 77% in both CD and UC. The difference was statistically insignificant. There was no significant difference in the sex ratio. The cancer rate was low. No gastrointestinal cancer occurred among patients with CD. Colorectal cancer was found in four patients with UC, three of whom presented with cancer on their first admission. It is concluded that recurrence and reoperation for recurrence in Crohn's disease have not impaired the prognosis compared to ulcerative colitis in this series.