Colorectal cancer screening reduces colorectal cancer incidence and mortality. This population-based study was conducted to evaluate (i) the association between subject factors and colorectal screening participation and (ii) the lifetime prevalence of colorectal screening among the general population of Ontario, Canada. Population-based controls were recruited by the Ontario Familial Colorectal Cancer Registry during 1998-2000. The 1944 persons completed an epidemiologic questionnaire. Descriptive statistics were computed and step-wise multivariate logistic regression was used to estimate odds ratios and 95% confidence intervals. Overall, 23% of persons greater than 50 years of age reported ever having had colorectal cancer screening; 17% reported fecal occult blood test (FOBT), 6% sigmoidoscopy, and 4% colonoscopy. Family history of colorectal cancer, increased age, higher household income, and use of hormone replacement therapy (among women) were all significantly associated with ever having had colorectal cancer screening. The low prevalence of colorectal cancer screening among the target population suggests the need for an increased awareness of the public health importance of colorectal cancer screening.