Whether conducted in a university or the healthcare field, research with human subjects gives rise to a multitude of ethical questions for healthcare professionals. While engaging in ongoing professional development on how to conduct research ethically, both clinicians and scientists need to expand their knowledge to provide answers to the following questions: Which ethical theories serve as a foundation for ethical principles in research ethics? What ethical principles should a researcher respect when conducting research with human subjects? What does it mean to conduct research ethically? What ethical dilemmas are encountered by a researcher in conducting research? This paper provides a review of ethical theories, and the ethical basis of guidelines developed and used to guide human subject research. Ethical behaviors and the personal responsibility of the researcher conducting research with human subjects are discussed along with the ethical considerations in research designs and methods.