The recent emergence of evidence-based medicine (EBM) presents medical ethics with the challenge of analyzing what is the current best medical evidence in ethical decision making. This article concludes that the use of the best available, most recently published research findings is a primary moral obligation. However, this does not automatically mean that the use of these research findings will lead to better ethical decision making. Research data can be distorted by methodological failings in the design and reporting of experiments, or by technical and commercial bias. Moreover, the introduction of norms, values, principles and ethical theories can lead to other choices than those proposed by empirical research findings. Ethical decision making must be informed and legitimated by the best available medical research. Nevertheless, ethical decision making is still primarily a choice based on values and norms.