Many epidemiological, clinical, and autopsy studies have demonstrated that the risk of sudden coronary death (SCD) is linked to the severity of coronary atherosclerotic lesions and to their thrombotic potential. However it remains unknown why some individuals manifest no clinical evidence of coronary disease until the onset of sudden death. The aim of this autopsy study has been to analyze the sociodemographic, clinical, and pathological features in case of sudden out-of-hospital coronary death where the death was the first manifestation of coronary disease. The results have been compared with those obtained from victims of SCD with known cardiac history. A total of 377 autopsies of sudden out-of-hospital cardiovascular deaths were performed at the Forensic Institute of Paris between 1989 and 1991. A total of 221 were SCD. A total of 160 of these subjects (72.4%) had no cardiac history (group A). The other 61 victims of SCD had cardiac antecedents (group B). Men account for 63% and 77% of the SCD in groups A and B respectively and are 12 years younger than women at the onset of SCD in both groups (65/77 years). Our study showed that in both groups SCD occurs in 83% of cases at home (and at rest) and in 30% of these cases while sleeping. Autopsy showed that SCD be it with or without antecedent occurs on a background of severe coronary disease with multivessels stenoses but coronary thrombosis was rarely observed (15%). SCD occurred in the context of underlying cardiomegaly.(ABSTRACT TRUNCATED AT 250 WORDS)