The purpose of this descriptive phenomenology is to investigate the participative experience of professional nurses in quality development and hospital accreditation. The data were collected from 15 professional nurses who were in the committee of hospital accreditation process in an accredited hospital. Bangkok. In-depth interviews were used for data collection. The data were analyzed by using colaizzi’s process. The study results revealed 4 themes. The first theme was giving the specific meaning of quality development and hospital accreditation. Nurses gave the meaning of quality development and hospital accreditation in the terms of the social quality acceptance and the systematic and collaborative work. The second theme was taking part in quality development and hospital accreditation. Most nurses who participated in the committee were selected by the head nurses. They felt bad at the beginning. They felt that quality development and hospital accreditation were complicated. confused, unhappy and overwhomed. When the time passing, they adapted themselves by self study searching information from textbook or internet, learning from experienced person, attending conference/ meeting and studying from other departments or hospitals. At the end, they changed their attitude to be positive in working. They realized that doing quality development and hospital accreditation was not complex and they were willing and being satisfied to do. Most nurses described characteristics of nurses who would join in the committee consisted of being accepted from the partners, having good skills in transferring data, having motivation, having knowledge in nursing care and information technology and being senior. The third theme was participative experience in quality development and hospital accreditation. Nurses took actions in the process of quality development and hospital accreditation by being as a core leader and following up the progress of the implement. Many nurses gained benefits from participating this work, such as, self development, being pround having good relationship among teamwork making the hospital being accepted form the society. Finally, the last theme was facing problems and obstacles in quality development and hospital accreditation The guideline was unclear There was a communication gap and a lack of mental support from the administrators. The study indicated that nurses were the important group in the hospital accreditation system because they were the majority of workers in the hospital who took care of and worked closly with patients Data from this study provide basic information for the hospital administrators and head nurses to understand and set up an appropriate plan prepare the participants and search for a good guideline to solve problems and obstacles for quality development and hospital development.