Total sales of dietary supplements and herbal medi- cines exceed two trillion yen in Japan. Approximately 60% of Japanese use dietary supplements or herbal medicines. In general, many people believe that dietary supple- ments and herbal medicines are safe natural prod- ucts; however, they could induce serious adverse events (bleeding, myocardial infarction stroke and glucose intolerance) in perioperative period. Coagulation and cardiovascular system can be nega- tively affected by those products. Thus careful preop- erative assessment is required for the patients who need regional anesthesia (e.g. epidural anesthesia and spinal anesthesia) and have cardiovascular complica- tions. Unfortunately there is no concise guideline regarding the use of supplements and herbal medicines during perioperative period. Anesthesiologists should be familiar with the adverse effects of dietary supplements and herbal medicines and pay more attention to non-prescribed medicines in preoperative assessment.