Studies of patient decision‐making use many different measures to evaluate the quality of decisions and the decision‐making process, partly to determine whether the ethical goals of informed consent, patient autonomy, and shared decision‐making have been achieved. We describe these measures, grouped under three main approaches, and review their limitations, leading to three conclusions. First, no measure or combination of measures can provide a complete assessment of decision quality. Second, the quality of a decision is best characterized vaguely, for instance as (...) “good,” “satisfactory,” or “poor,” and these categorizations depend on qualitative judgments that go beyond quantitative measures. Third, bioethicists should focus on identifying and addressing poor or problematic decisions, rather than trying to incrementally increase decision quality, quantified by a measure. Decision‐quality measures can be useful in research and in advancing important goals of bioethics, as long as the challenges of defining and measuring decision quality are recognized. (shrink)