The authors' aim is to outline some of the main medico-legal problems in cardiology, especially those regarding the premature hospital discharge of patients with undefined chest pain and/or with acute myocardial infarction. After a brief overview on the etiology and clinical definition of chest pain and myocardial infarction, premature hospital discharge is defined and the incidental medico-legal risks that physicians operating in such situations are exposed to are pointed out. Next, the profiles regarding both the positive and negative views of professional medical responsibility are described. In the negative frame, the authors outline the most frequent civil and penal aspects of the unpremeditated responsibility. Then the physician's error, in both qualitative (generic or specific guilt) and quantitative (degree) terms, is considered; particularly, negligence, imprudence and inexperience, as qualitatively accepted meanings of generic guilt, are dealt with by adopting illustrative cases settled in the light of the right legal interpretation. The phases of the diagnostic or prognostic error are evaluated, and clinical protocols, as a reference parameter for the identification of error, are considered. Lastly, the problem of causality, essential condition for the judgment about the professional responsibility, and the problem of the patient's consent, including an evaluation of the legal capability or incapability about the declaration of consent, are examined closely.