The paper consists in a report of a retrospective study (of data from 1987) on the prevalence of benzodiazepines in blood at the time of death. Of 2,007 autopsies, forensic chemical analyses were performed in 1,587 cases, in 159 of which benzodiazepines were found. Of these 159 deaths, 22 were considered to be due to natural causes, and in another 22 cases the cause of death was still unclear after examination; the remaining 115 deaths were due to accidents (N = 16), suicide (N = 60), drug addiction (N = 29) or alcoholism (N = 10). Multiple benzodiazepine intake was found in 37 cases, a subgroup including all 29 cases of death due to drug addiction. In a comparison of suicides and natural deaths, the concentrations both of flunitrazepam and nitrazepam were significantly higher among the suicides (P < 0.001 and P < 0.05, respectively). In four cases, the sole cause of death was benzodiazepine intake. It is concluded that some benzodiazepines, particularly flunitrazepam, may be more toxic than formerly supposed.