BACKGROUND Kampo (Japanese herbal) medicine is the complementary and alternative medicine that is most frequently used by Japanese doctors. We studied the perceptions and attitudes of Japanese gynecologic cancer patients to Kampo medicines and analyzed the characteristics of the backgrounds of Kampo users. METHODS A total of 476 patients with gynecologic cancer completed a self-reported questionnaire on Kampo medicine. State anxiety and trait anxiety were also assessed using the State-Trait Anxiety Inventory. RESULTS It was confirmed that 22.9% of the women had used Kampo medicine. Kampo users were more likely to have had chemotherapy and were more likely to have experienced uncomfortable side effects of cancer treatment. Kampo users were more likely to believe that 'Kampo offers relief of symptoms,' 'fewer side effects than Western-style medicine,' and 'is not less effective than Western-style medicine' than nonusers. Kampo users expressed a stronger attitude of 'I want to take Kampo medicine.' Multiple risk ratio regression analysis revealed that chemotherapy (RR, 1.82; 95% CI, 1.14-2.91), lower state anxiety (RR, 0.76; 95% CI, 0.58-1.00), and higher trait anxiety (RR, 1.46; 95% CI, 1.11-1.92) were independently associated with Kampo use. CONCLUSIONS This study showed that slightly less than one-fourth of Japanese gynecologic cancer patients take Kampo medicine. Kampo users made more favorable comments on Kampo medicine than nonusers. Our findings suggest that the psychological characteristics of individual patients is one of the factors that can influence the usage of Kampo.