The use of complementary alternative therapies in cancer patients are increasing with the increase in cancer incidence and treatment rates. Studies were conducted to find out about cancer patients’ knowledge and attitudes (treatment effect, intention to use) towards complementary and alternative therapies. 10 complementary alternative therapies (hyperthermia, ascorbate, thymosin, mistletoe, immunocyanin, selenium, Phellinus linteus, cholecalciferol, glutathione, herb remedies) were selected from evidence review. 100 patients who visited cancer care hospitals were surveyed about their knowledge and attitudes (effectiveness, treatment choices) by self-questionnaire. The total score for knowledge/attitude (effectiveness/intent to use) towards complementary and alternative therapies was 25.4 points (26.7 points/24.7 points, out of 40). Knowledge and attitude scores for hyperthermia were the highest, and knowledge and attitude scores for immunocyanin and glutathione were the lowest. Herbal remedies scored higher on knowledge but lower on attitude (effectiveness and choice). Vitamin C had moderate knowledge and effectiveness scores, but the highest intention-to-use score. There was a negative correlation between the effectiveness of complementary and alternative therapies and the choice of treatment regimen with lower scores as people aged. The use of complementary alternative therapies is increasing although the evidence has not been proven for the cancer cure rate or survival. It is necessary to recognize the effectiveness and limitations of complementary alternative therapies and educate patients so that they can choose the appropriate treatment. Further research is needed on the effects and side effects of various complementary alternative therapies used in addition to standard treatments.