Due to the close relationship between the meaning of quality and clinical competence and also improving quality of nursing services by increasing clinical competence, this study was conducted with the goal of determination of self-efficacy in clinical competence of nursing students as well as its relationship with demographic characteristics. The descriptive-analytical study was carried out at Tabriz medical university in academic year 2012-13. For collecting data, the Self-efficacy Questionnaire was used for Professional Nursing Competence, and it was also included 181 items and provided in six areas namely relationship between nurse-patient, health promotion, disease/injury prevention, supportive care, rehabilitation care, and professional performance area. In addition, statistical analysis of data was done by applying SPSS13 software Based on the findings, average level of self-efficacy in professional nursing competence was 68.10±14.50. Among related areas, professional performance area (73.02±16.42) was at the highest level while health promotion area (64.78±16.66) was at the lowest level. In this study, relationship between gender and self-efficacy in professional nursing competency was meaningful (P = 0.01); by noticing that self-efficacy in professional nursing competence was at the middle level, therefore, it is required that nursing program improve based on achieving clinical competence in order to increase students’ self-efficacy. Moreover, gaining nursing competency should be added as a part of nursing assessments.