Modern molecular biology and clinical genetics have the ability to diagnose many diseases, the presence or absence of which is important in various areas of forensic medical opinion. The aim of the study is to present examples of possible non-standard application of clinical molecular-genetic tests in forensic medicine. From among all the opinions prepared so far at the Department of Forensic Medicine in Katowice, three were selected two of which concerned post-autopsy conclusions relating to the cause of death, and in one case - opinion based on the files of a case related to the suspicion of a maltreated child syndrome in an infant. In all these cases, the results of the molecular and genetic tests were negative, which was taken into account by the experts when formulating the final conclusions of the opinion. The use of clinical molecular and genetic tests in forensic medicine is possible and always brings important additional information that broadens the possibilities of opinion-making and facilitates diagnosis. The areas in which this type of research may be particularly useful are: diagnostics of the basis of thromboembolic complications, modern integrated morphological and molecular diagnostics of neoplasms and diagnostics of genetic defects of connective tissue in children suspected of having abused child syndrome.