Colorectal cancer affects more than 157,000 Americans annually. Occupational risk from exposure to asbestos dust has been implicated, leading us to explore further the possible association between colorectal cancer and asbestos. Two hundred sixty-one cases of colon and rectal cancer and 183 control cases were identified within a large, population-based case-control study conducted in southeast Michigan. Employment in occupations historically known to involve heavy exposure to asbestos was used as a surrogate for asbestos exposure. Cancers of the colon showed reduced odds ratios. Our findings differ substantially from those of the previous studies showing elevated risk. Further study is needed to address the same question, with specified asbestos exposure assessment and control for potentially significant confounders such as physical activity and diet.