BACKGROUND: The ethical guidelines and ethical atmosphere of the hospital affect the quality of nursing care. Improving the health of patients in most cases depends on the observance of ethical points and ethical behaviors by nurses. The aim of this study was to determine the effect of hospital ethics and ethical training guidelines on improving the quality of nursing care and nurses' professional ethics. MATERIALS AND METHODS: This is a descriptive-analytical study. This study was performed by multi-stage relative cluster sampling on 260 qualified nurses in 2014. Data were collected using the Hospital Ethical Climate Questionnaire and the Judgments about Nursing Decisions Questionnaire and analyzed using SPSS software version 19. RESULTS: The results showed that nurses' perceptions of the ethical climate of hospitals were relatively positive. The ethical behavior of nurses was moderate and good. Nurses' perception of the ethical climate scores was not related to the ideal ethical behavior of nurses (r = 0.11, P = 0.86).The ethical climate perceptions of nurses were related to real workplace ethical behavior score (r = 0.188, P = 0.002). The results also showed that ethical guidelines can improve the quality of nursing care. CONCLUSION: Considering the results of this study, it seems that holding nursing ethics training programs can be a big step toward promoting the professional behavior of nurses and the observance of professional ethics by nurses.