AIMS AND OBJECTIVES:This paper is a report of a study conducted to investigate differences between nurse practitioners' perceptions of the importance of required competencies and their self-evaluated existing competencies, and the main factors influencing these differences. BACKGROUND:The difference between nurse practitioners' perceptions of required competencies and their existing competencies has never been investigated. Therefore, it is still uncertain whether these two competencies differ. DESIGN:A nationwide survey study was authorised by the Department of Health (DOH) in Taiwan. METHODS:For this nationwide survey study, the Questionnaire of Competencies in the Nurse Practitioner's Role was mailed to all nurse practitioners who qualified for the first annual national NP licence exam in Taiwan. Of 582 questionnaires distributed, 374 valid questionnaires were returned for a response rate of 64.2%. RESULTS:The scores for required competencies were all higher than existing competencies. The competencies with largest differences were (in increasing order) clinical research, direct care, and leadership and reform. The competencies with smallest differences were (in ascending order) medical assistance, communication and coordination, and ethical decision-making. Differences in the total score between required and existing competencies were significantly influenced by nurse practitioners' age, seniority as nurse practitioner, whether the nurse practitioners' institution had a nurse practitioner advancement system, and the number of patients under their care. CONCLUSIONS:Nurse practitioners' perceptions of the importance of their expected role competencies were significantly greater in most cases than their actual competencies. RELEVANCE TO CLINICAL PRACTICE:These findings could serve as a reference to improve cultivation of the NP system in Taiwan, to strengthen professional competencies in NP training programs.