The commercial availability of genetic tests for colon cancer susceptibility is creating new opportunities and challenges for both patients and providers. To provide information useful in the education and counseling of individuals considering genetic testing, we conducted structured interviews with 45 male and female first-degree relatives of colorectal cancer patients. Fifty-one percent of respondents indicated that they definitely would want to obtain a genetic test for colon cancer susceptibility when it is available and 31% said that they probably would want to be tested. Interest in genetic testing was significantly higher among persons with less formal education and those with a Catholic religious preference. Motivations for genetic testing included the following: to know if more screening tests are needed, to learn if one's children are at risk and to be reassured. Barriers to testing included concerns about insurance, test accuracy and how one's family would react emotionally. Most participants anticipated that they would become depressed and anxious if they tested positive for a mutation, while many would feel guilty and still worry if they tested negative. Of note, about one-half of respondents expected that they would decrease their use of screening tests and make fewer attempts to reduce dietary fat if they tested negative. These preliminary results underscore the importance of educating patients about the potential risks, benefits and limitations of genetic testing, with particular emphasis on the possibility of adverse psychological effects and implications for health insurance. The potential for false reassurance following a negative test result should be addressed by emphasizing the residual risks of cancer among non-carriers of predisposing mutations.