Previously, Phase I studies in Japan were conducted after doing phase I trials in the West. However, the opportunity that phase I in Japan which are conducted in parallel with the West or after a few cohorts in the West have increased at present. In addition, first time in man (FTIM) studies are increasing in Japan stand alone or in collaboration with overseas medical institutions. In view of these circumstances, expectations for clinical sites about performing phase I studies are described by use of some examples from pharmaceutical company perspective so that conducting Phase I studies are promoted in Japan. First of all, in phase I study, especially FTIM study, only pre-clinical data are available for toxicity profile. Therefore, in order to ensure the safety of subjects, inspection in other departments such as circulation, ophthalmology, dermatology and emergency preparedness are required. Regarding of the patient recruitment, enrollment speed is extremely important even thought additional patient entry happens. Therefore, not only coalition of each department in study site but also network with other hospitals is critical element in order to assure candidate patients.Thirdly, it is important to build up supportive and cooperative structure of site staff who engaged in the trials. In Japan, collaboration with not only clinical research coordinator but also nurse in-patients ward is necessary for Phase I studies because in-patient treatment is typically required.In addition, English Communication skill, quick data input to EDC, facility of teleconference, etc. are essential for Safety Review Committee for dose escalation as well. Finally, it is occasionally unclear regarding training log for site staff, approval process and record of documented procedures. Therefore the improvement is also needed for these points.