Background: This study attempts to understand if medical providers beliefs about the moral permissibility of honoring patient-directed refusals of life-sustaining treatment (LST) are tied to their beliefs about the patient’s decision-making capacity. The study aims to answer: 1) does concern about a patient’s treatment decision-making capacity relate to beliefs about whether it is morally acceptable to honor a refusal of LST, 2) are there differences between provider types in assessments of decision-making capacity and the moral permissibility to refuse LST, and (...) 3) do provider demographics impact beliefs about decision-making capacity and the moral permissibility to refuse LST. Methods: A mixed-methods survey using Likert assessment and vignette-based questions was administered to medical providers within a single health system in the upper Midwest (N = 714) to assess their perspectives on the moral acceptance and decision-making capacity in cases of withholding and withdrawing treatment and suicide. Results: Behavioral health providers report accepting of the moral permissibility of suicide (91.2%) more than either medical providers (77.2%) or surgeons (74.4%) (n = 283). Decision-making capacity was questioned more in the vignettes of the patients refusing life-saving surgery (36%) and voluntarily starvation (40.8%) than in the vignette of the patient requesting to deactivate a pacemaker (13%) (n = 283). Behavioral health providers were more concerned about the capacity to refuse life-saving surgery (55.9%) than medical providers (33.8%) or surgeons (23.1%) (n = 283). Conclusions: Respondents endorse the moral permissibility of persons to withhold or withdraw from treatment regardless of motive. Clinical concerns about a patient’s treatment decision-making capacity do not strongly correlate to views about the moral permissibility of honoring refusals of LST. Different provider types appear to have different thresholds for when to question treatment decision-making capacity. Behavioral health providers tend to question treatment decision-making capacity to refuse LST more than non-behavioral health providers. (shrink)