The present study analyzes time trends of inflammatory bowel disease (IBD) in England-Wales and the United States based on nationwide hospitalization statistics. Because these statistics cover the total population of each country, they may give a more representative picture of the true trends than previous analyses concerning only one region or health center. The Hospital In-patient Enquiry was used to evaluate time trends in England-Wales from 1962 to 1985, data from the National Hospital Discharge Survey and the Commission on Professional Activities were used for trends in the United States from 1970 to 1987. A rise of Crohn's disease persisted unabated in the old age groups throughout the observation period. It was less marked in those aged under 35 and reached a plateau during the most recent decade. In ulcerative colitis, discharge rates increased in the older age groups, but remained constant or declined in the middle or younger age groups, respectively. Similar trends were observed in all three surveys. The hospitalization data confirm similar age-specific trends of mortality. The difference between younger and older age groups suggests that generations born 60-80 years ago have become more likely to be affected by IBD leading to hospitalization and mortality. As these high-risk generations grow older, there is a relative rise of hospitalization and mortality from IBD in these subjects.