BACKGROUND: It is well-known that patients with chronic fatigue or frequent pain seek complementary and alternative medicine therapies (CAT) in Western countries. We conducted this study to determine the pattern of CAT use and the factors related to CAT use in patients with chronic fatigue or pain in Korea. METHODS: This was a cross-sectional study. The participants (n = 143) with chronic fatigue or pain completed a self-reported questionnaire including demographic characteristics and lifestyle as well as disease-related and CAT-related items. RESULTS: The frequency of CAT use was 51.0& and 39.2& over the past 10 years and 1 year, respectively. The most common type of CAT used was herbal medicine. The therapeutic effects of the CAT were similar to physicians' prescriptions. CAT were most often used in combination with conventional medicine rather than alone. More than 70.0& of subjects did not consult their physicians for the use of CAT. The duration of illness, severity of fatigue and pain was signifi cantly related to the use of CAT. CONCLUSION: Many patients with chronic fatigue or pain use CAT. Most of these patients do not consult their physicians regarding CAT use.