Data were obtained from autopsy investigations, toxicological analysis of blood and urine, and police reports. Only cases with detectable morphine and 6-monoacetylmorphine (6-MAM) in blood were included in the study in order to select heroin intoxication cases. The findings indicate that for two-thirds of the 192 cases, death occurred in a public place and usually without any time delay. The blood concentrations of morphine ranged from 50 to 1,200 ng/g and of 6-MAM from 1 to 80 ng/g. Codeine was detected in 96 percent of the subjects. For the majority of cases, the forensic investigations found evidence of polydrug use, with the most common additional drugs being alcohol and benzodiazepines. In one-quarter of the cases, however, other drug combinations were found. Previous abstinence from heroin and use of alcohol were identified as risk factors for sudden death from heroin injection. For 6-MAM there was also a correlation with the presence of THC and benzodiazepines. Despite a high frequency of heart abnormalities (e.g., myocarditis and focal myocardial fibrosis), these conditions did not correlate with morphine or 6-MAM blood concentrations. The study thus indicates that alcohol intake and loss of tolerance for heroin are risk factors for death from heroin use; no connection to heart pathology was found. The authors advise that future studies should focus on other possible risk factors and examine whether benzodiazepines constitute a risk factor for fatal outcome from heroin injection. 4 figures, 4 tables, and 37 references