Consent to medical treatment is a patient right. The patient right to give or withhold consent to some treatment procedure arises from the principle of free will of each person, that is, the principle of self-determination. The patient consent is valid only in case he/she has previously been provided by the physician with the relevant information on the intended medical measure. The scope of information is generally regulated. However, the physician is obliged to estimate each patient's need and the ability to receive information. Treatment can have desired results only with patients' compliance. Apart from being patient right, giving of consent to medical treatment is also his/her legal duty, the fulfillment of which is expected prior to beginning of treatment. By non-complicance, a patient unable the treatment procedure and damages his/her own health. However, the duty to give the consent is not the real legal obligation. It cannot be the subject of claim, nor can it be coercively enforced. For this reason, consent to medical treatment, as well as the other subsidiary duties of patients, is named duty of the patient in his own interest. Its non full filament does not lead to the liability of the patient. It can, under certain circumstances, reduce or exclude the physicians share in damage and his liability or, under certain circumstances, give the possibility to the physician to cancel further rendering of health care to the patient.