Background: The implementation of ethical principles is crucial in carrying out nursing care, since it is part of the 12 basic competencies, that should be possessed by a nurse. This study aims to analyze the factors associated with the implementation of nurses' ethical principles.Design and Methods: This study used a quantitative research design, with a cross-sectional approach. The participants consisted of 389 nurses, working in the medical ward of the hospitals, in Indonesia. Data were analyzed using the bivariate analysis, t-test, ANOVA and multiple linear regression test.Results: There were no significant relationships between the demographic factors and the ethical behaviour. There was a relationship between caring behaviour and the application of ethical principles (p=0.000, and a correlation coefficient of 0.602).Conclusion: Nurse ethical behaviour was improved, by increasing their caring attitude.