This paper presents clinical evaluation of the KAIST-Ewha Colonoscopy Simulator II that is extended from the previous version jointly developed by KAIST and Ewha Womans University. Realism validation was carried out twice before the clinical evaluation. Nine fellows and six residents participated in this part of clinical evaluation study, and they were divided into two groups, simulation-trained and control groups. The control group was assessed through five colonoscopies to actual patients under supervision before starting the traditional patient-based training. They will be assessed again after the regular training is over. The simulation-trained group is being trained with two specially designed training scenarios. The subjects in this group will be also assessed through five colonoscopies to actual patients after completing the training. The study is in progress, and this paper reports preliminary results of the study.