It has been suggested that some occupational groups have a high risk of contracting chronic inflammatory bowel diseases. A cohort, comprising 2,273,872 male and female Danes aged 20-59 on 1 January 1981, and a cohort similarly defined as of 1 January 1986 were followed up for hospitalizations due to chronic inflammatory bowel disease until 31. December 1990. From 1981 to 1990, 6296 first time admissions occurred. Among 15 groups previously found to be at high or low risk only female office staff and health personnel had statistically significantly increased standardized hospitalization ratios. Occupations with non-daytime work did not have an increased risk. Occupations with predominantly sedentary work had a standardized hospitalization ratio of 125 (95% confidence interval 116.9-133.1) compared to occupations without sedentary work. Self-employed had low hospitalization rates, while 'other salaried staff' and "not economically active" had high rates.