PURPOSE The purpose of this study was to study complementary and alternative medicines (CAM) used among cancer patients in Korea. METHOD This study was a descriptive survey. Study participants were 1,150 cancer patients selected from 28 representative hospitals in Korea. Data were collected between December 1, 2004 and March 30, 2005. RESULTS Their diagnosis were as follows : 20.0% for breast cancer, 15.6% for stomach cancer, 14.4% for liver cancer, 10.8% for lung cancer, 10.0% for colon cancer, and 10.0% for uterine cancer. 75.0% of cancer patients had used CAM. The most popular categories of CAM use were diet with 153.2%, non-prescription of oriental medical doctor 47.9% and mind-body control 20.3%. CAM use gender, age, cancer type, cancer treatment method, and current treatment type was significantly different in. CONCLUSION CAM use among cancer patients in Korea was very popular (75.0%) and so systemic guidelines of CAM use are needed.