BACKGROUND: Studies on incidence rates of first-time colonic diverticular disease are few, and population-based estimates of lifetime risk are lacking. In this observational study, the incidence, admission rates and lifetime risks of hospitalization and surgery for diverticular disease were investigated. METHODS: Considering the entire Swedish population as an open cohort, incidence and admission rates, and lifetime risk estimates (considering death as a competing risk) of hospitalization and surgery for diverticular disease were calculated using data from cross-linked national registers and population statistics from 1987 to 2010. RESULTS: In total, there were 144 107 hospital admissions for diverticular disease in 95 049 individual patients. Of these, 17 599 were admissions with bowel resection or stoma formation in 16 824 patients. The total number of person-years in the population during the study period was 213 949 897. Age-standardized incidence rates were 47·4 (95 per cent c.i. 47·1 to 47·7) for first-time hospitalization with diverticular disease and 8·4 (8·2 to 8·5) per 100 000 person-years for diverticular disease surgery. The corresponding admission rates (including readmissions) were 70·8 (70·4 to 71·2) and 8·7 (8·6 to 8·9) per 100 000 person-years. Following an increase in 1990-1994, rates stabilized. Based on incidence and mortality rates from 2000 to 2010, the estimated remaining lifetime risk of hospitalization from 30 years of age was 3·1 per cent in men and 5·0 per cent in women. The corresponding risk of surgery was 0·5 per cent in men and 0·8 per cent in women. CONCLUSION: Diverticular disease is a common reason for hospital admission, particularly in women, but rates are stable and the lifetime risk of surgery is low.