Background and Objectives: Study of clinical competence in nursing helps determine the quality of health care delivered to patients. Given the priority of observance of principles over caretaking and necessity of spirituality existence at the core of health care provision, this study was conducted to investigate clinical competence and its relationship with professional ethics and spiritual health in nurses. Methods: In this cross-sectional, descriptive, and correlational study, 281 nurses were enrolled by consensus sampling. Sampling was conducted from February, 2016 till June, 2016. The data were gathered by a demographics questionnaire, a self-assessment scale of clinical competence, a nursing ethics questionnaire, and a spiritual health questionnaire, and analyzed by descriptive statistics and t-test, Pearson's correlation coefficient, ANOVA, and linear regression analysis in SPSS 21. Results: The total scores for self-assessment scale of nurses' clinical competence, professional ethics, and spiritual health were moderate. In the light of the results of Spearman's correlation coefficient, there was a significant and positive correlation between clinical competence and spiritual health. Moreover, a significant positive correlation was observed between professional ethics and spiritual health but there was no correlation between professional ethics and clinical competence. Conclusion: Managers' and personnel's Knowledge about the level of nurses clinical competence, professional ethics, and spiritual health in teaching health care centers provides valuable information to develop in-service and efficacious education programs and ultimately to improve the quality of nursing services.