The success of population screening for CRC depends largely on public uptake. Available strategies differ in multiple dimensions of process and outcome. OBJECTIVE: To measure patient preferences for CRC screening attributes and estimate willingness to pay (WTP) for changes in attribute levels using a discrete choice experiment ("conjoint analysis"). METHODS: Six key attributes of CRC screening strategies were identified through structured focus groups. Questionnaires included 10 choice sets based on a fractional factorial design to maximize D efficiency. Surveys were mailed to a random sample of patients aged 40-60 years from an Ontario primary care network (response rate = 51% (547/1074), 88% of whom completed all 10 choice sets (n = 485)); b coefficients from regression analyses estimated the marginal utilities of attribute levels from which WTP was calculated. Differences among subgroups were tested using likelihood ratio tests. RESULTS: Respondents had the strongest preferences for sensitivity, with the highest utility for high sensitivity and the lowest utility for low sensitivity. Individuals would be willing to pay an additional CDN$910 (~US$640) for a test with high vs. low sensitivity. Following sensitivity, respondents had the highest preferences (in descending order) for specificity, preparation, pain, and price. Preferences differed significantly by gender, age (<50 yrs vs. > 50 yrs), income ( < $50,000 vs. > $50,000) and education (high school or less versus college or higher). In follow-up questions for each choice set where individuals were asked if they would prefer no test, 26% of respondents chose no testing in more than 5 of their 10 choice sets. CONCLUSIONS: Results show a wide range of marginal utility for attribute levels of CRC screening tests, and many respondents preferred no test. Better understanding of patient preferences can help improve the design, promotion and uptake of CRC screening programs.