Nursing is a manifestation of a value according to which it is morally good to promote physical and psychological well-being. Such a moral obligation involves making judgements. Ethical judgements are the decisions a person makes on whether a particular act is right or wrong. Ethical principles serve as the basis for ethical rules and as a framework for decision-making. Ethical theory provides a rationale that explains the principles and rules in order to provide a structured approach to ethical reasoning. Although ethics is not a science with verifiable answers, a knowledge of ethical theory enables nurses to make decisions in a manner that is more comprehensive and well reasoned than is opinion or intuition. In this paper, an overview of ethical theories, ethical principles and influences on ethical or moral reasoning is presented as well as the ethical decision-making process.