Remarkable progress has been made in surgical techniques and instruments, and the significance of clinical studies as a method to assess them is increasing. Recently, the long-term results of the randomized, controlled trial of laparoscopic and open surgery for colon cancer JCOG0404 have been reported. Although the survival results were good in both the laparoscopic and open groups, the noninferiority of laparoscopic surgery was not demonstrated. Noninferiority comparisons are not easy to understand. This article considers nohinferiority tests and their difficulty from a clinician's viewpoint In addition to problems with noninferiority tests, clinical trials in the surgical field involve many considerations, such as assessments of surgical quality, issues in double blinding, patients' unwillingness to participate, the occurrence of learning curves, etc. Considering the uniqueness of surgical clinical studies, the author comments on the necessity of randomized clinical trials, importance of prospective and retrospective observational studies, and significance of noninferiority trials and large studies. For the future development of surgery, clinical studies are one of the most important areas of focus, and a thorough understanding of clinical studies and driving studies is necessary.