Study feasibility is a key step for clinical trials and this process/action is critical impact for the successful of conducting clinical trials or not. Therefore, how to conduct the proper study feasibility is become the important topic for clinical trials during startup phase. Though this training, I will go through the definition of study feasibility and use 5W1H approach to brief why, what, whom, where, when and how to conduct the study feasibility. I also plan to share the best practice and most frequent asked questions to all attendees for better understanding or clarifications. During the training section, I will include some real cases from my personal experience to explain the concepts and link to actual situation once you need to conduct the study feasibility. Hope this training can benefit for all members who is playing the roles in clinical trials not only from sponsors’ end but also from investigators’ or site staffs’ perspective.