In the result of a workshop held in Münster on 1st May 1993, 23 institutes of legal medicine in Germany reported death cases where the primary supposition was natural death or a death without legal relevance, but where the autopsies by chance revealed an unnatural death or a death with legal relevance. In the institutes participating in the study 13,000 autopsies were performed during the period of the reports, i.e. 75% of all legal autopsies performed in one year in Germany. A total of 92 "discoveries by chance" were reported where a natural death was given on the death certificate after the external examination of the corpse among them 49 accidents, 10 homicides, and 19 deaths by medical implications. In 717 deaths the manner of death was certified as "unclear" on the death certificate, but the autopsy revealed an unnatural manner of death. Some of these cases are also "discoveries by chance" after serious medical errors during the examination of corpses. Among these 717 cases were 35 homicides. It seems remarkable, that the prosecutors did not order a toxicological examination in several cases of fatal intoxications. Furthermore the results show that doctors often overlooked signs of carbon monoxide poisoning during the external examination of corpses. From errors made during the external examination another group of cases resulted which were initial classified as unnatural death without legal relevance, but the autopsy surprisingly revealed relevant facts. Finally in 29 autopsies carried out after exhumation evidence of homicide was found in 3 cases. On the basis of this multicentre study it can be estimated that there are at least 1200 homicide cases or 11,000 cases of unnatural death per year which do not appear in the official statistics and have been classified as natural death. The considerable grey area of fatal cases in connection with medical intervention resulting from the study (n > 2000) is also alarming. In addition at least 100 undiscovered homicides are certainly included in the group of death cases certified as unclear during the external examination and where no autopsy was performed. Sources of the grey area are essentially errors made during the external examination of corpses and to a lesser degree incorrect decisions to release the corpse, mistakes were seldom made also by doctors performing the autopsy. The study shows a considerable grey area of unnatural death cases, which exists within the modern society of Germany. In face of this emphasis must placed on the historical demands of criminologists and forensic pathologists: reinforced education and further education of medical students and doctors in the field of the external examination of corpses. Introduction of a specialized medical external examination of corpses Adherence to the 3 classical classifications of the manner of death: natural, unnatural and unclear on the death certificate. Increased number of autopsies.