Cases of sudden death without prior noticeable clinical symptoms and morphological indicators found at autopsy pose serious problems in medico-legal opinionating. Developing an expert opinion is practically impossible if the body has not been autopsied, as well as in cases, when no histopathological and chemical-toxicological tests have been performed. In the course of proceedings aiming at establishing a given event as a work accident and address the issue of compensation claim, courts of labor and insurance claims, as well as civil courts often demand determination of the cause of death by answering whether the demise resulted from a myocardial infarction or whether the death may be regarded as an accident at work. The authors present problems associated with opinion formulation that are faced by the expert and propose their own model of establishing an opinion in the above mentioned cases