Purpose We surveyed prostate cancer patients about complementary and alternative medicine (CAM) use and evaluated patient factors that correlated with CAM use 6 months following diagnosis. Methods The Prostate CAncer Therapy Selection study was a prospective, observational multi-site study of men’s treatment decision-making process after a diagnosis of local stage prostate cancer. Recruitment occurred in community urology practices in Washington State, hospital-based urology clinics affiliated with the University of Southern California, and Kaiser Permanente in Northern California. Eligible study participants included men over age 21 diagnosed with local stage prostate cancer between May 1, 2005 and December 31, 2006. Results Fifty-two percent of survey respondents (379) reported using one or more types of CAM. Of the patients, 51% used one CAM method, 26% used two methods, and 23% used three or more methods. The most commonly reported category was mind–body therapies (65%). Only 43% of patients discussed their CAM use with a health professional; of those, 20% informed their primary care physician and 30% told the doctor managing their prostate cancer care. Less than half thought the CAM they used was “very helpful”, but a majority thought it was somewhat helpful for their condition. Conclusions Further research is needed to characterize the goals prostate cancer patients have for CAM, whether the treatments met those goals, and how this translates into the perceived helpfulness of these therapies. The implications of patients not discussing CAM use with health professionals at the time of prostate cancer treatment need further studies.