Purpose: This study was conducted to examine utilization of alternative therapies and understand decisional criteria related to use of alternative therapies among chemotherapy patients. Method: Data were collected from 165 cancer patients through the use of questionnaire and interviews at the chemotherapy treatment rooms of two general hospitals located in Seoul. Result: Sixty point six percent of subjects after cancer diagnosis have experience of using alternative therapies and 39.4% were still using alternative therapies. On the average the patients used alternative therapies for 9.4 months and they paid 483,000 Won per month for alternative therapies. Decisional criteria related to use of alternative therapy were curability, social group influence about alternative therapy, confidence in alternative therapy, present symptoms, and who decide on the use of alternative therapy. These variables in the alternative therapy group were statistically different from those of the hospital treatment only group. Conclusion: Utilization rate of alternative therapy among chemotherapy patients is high and cost burden is heavy. Thus, they need to be educated about utilization of alternative therapy by nurse and medical personnel.