The sojourn time of preclinical colorectal cancer is a critical parameter in modeling effectiveness and cost-effectiveness of colorectal cancer screening. For ethical reasons, it cannot be observed directly, and available estimates are based mostly on relatively small historic data sets that do not include differentiation by age and sex. The authors derived sex- and age-specific estimates (age groups: 55-59, 60-64, 65-69, 70-74, 75-79, and ≥80 years) of mean sojourn time, combining data from the German national screening colonoscopy registry (based on 1.88 million records) and data from population-based cancer registries (population base: 37.9 million people) for the years 2003-2006. Estimates of mean sojourn time were similar for both sexes and all age groups and ranged from 4.5 years (95% confidence interval: 4.1, 4.8) to 5.8 years (95% confidence interval: 5.3, 6.3) for the subgroups assessed. Sensitivity analyses indicated that mean sojourn time might be approximately 1.5 years longer if colorectal cancer prevalence in nonparticipants of screening colonoscopy is 20% lower than prevalence in participants or 1 year shorter if it exceeds the prevalence in participants by 20%. This study provides, for the first time, precise estimates of sojourn time by age and sex, and it suggests that sojourn times are remarkably consistent across age groups and in both sexes.