There are situations in which refusal to provide treatment according to a patient's request may be justified by ethical rules and principles of medical ethics. This article explores such situations, analyzing the various factors which a physician may consider when refusal to provide treatment is at stake. The article focuses on three major states of affairs under which the question of whether a physician has liberty to refuse to treat may occur: refusals deriving from conflicts between the physician's personal values and ones reflected in the proposed treatment; refusals stemming from general considerations to be classified as policy reasons; and refusals following a clinical assessment as to the proposed treatment, expected chances of recovery and expected benefit to the patient. The ethical analysis of the article leads to the conclusion that a physician may (although he/she does not have a right to) refuse to provide medical treatment following a patient's request when the physician's refusal originates in conscientious resistance. However, the physician may not refuse to treat when refusal is based on policy considerations or concerns third parties not immediately involved in the physician-patient relationship. In addition, a physician may refuse to provide treatment following a medical assessment when and if the proposed treatment is not urgently required, if the provision of treatment may create risks to the patient's health, if its conferral may inflict pain or suffering exceeding its expected benefits to the patient, or the proposed treatment is futile and its chances to combat the disease are significantly minimal.