Objectives: To investigate in depth the use of complementary and alternative medicines (CAMs) by cancer patients at the end-of-life (EOL) and how they communicate with physicians about them. Design and location: In 17 hospitals in Korea between January and December 2004 we identified 4,042 families of cancer patients. Results: The prevalence of CAM use among cancer patients at the EOL was 37.0%, and 93.1% had used pharmacologic types of agents. The most frequent motive for CAM use was the recommendation of friends or a close relative (53.4%) or a physician (1.6%). Only 42.5% discussed CAM use with their physicians. Satisfaction with CAMS was recalled for 37.1%. The most common reason given for that satisfaction was improvement of emotional or physical well-being, while ineffectiveness was the most common reason given for dissatisfaction. The average cost of CAM during the last month of life was $US 900. CAM use was associated with longer disease periods, primary cancers other than liver, biliary, and pancreatic, and need of support from physicians or religion. Conclusions: CAM use among cancer patients at the EOL was common, not discussed with physicians, and associated with expectation of cure. Expectations were generally unmet while the treatments were a financial burden. Further studies evaluating the effects of CAM at the EOL and factors that enhance communication with the physician are needed.