The study found that licit and illicit substances were strongly associated with suicide, even when the suicide method did not involve a deliberate drug overdose. Consistent with earlier research, substances were frequently present in the subjects and in proportions far in excess of what would be expected among the general population. Substances were present at 4.6 (alcohol), 5.6 (cannabis), 10.0 (methamphetamine), and 41.4 (heroin) times these levels in the general population. One in 6 cases was noted to have a history of drug and alcohol dependence, and 1 in 10 was a known injecting drug user. These findings are consistent with studies that indicate dependent drug users most often use suicide methods other than overdose. Consistent with the epidemiology of substance use, alcohol and cannabis were the most commonly detected substances. There were notable differences in the prevalence of substances across suicide methods. Of particular note was the relationship between psychostimulant use and gunshot death. Hanging was the most common method, accounting for 51 percent of cases nationally, with gunshot accounting for 7 percent (firearms ownership is restricted in Australia). The increase in the prevalence of methamphetamine among cases across the study period is cause for concern. Only one-third of known psychotic cases had antipsychotic medications in their blood at the time of death; 1 in 10 of these cases tested positive for cannabis, and 1 in 20 for psychostimulants. The use of these substances may have increased both psychotic symptoms and proximal suicide risk. 2 tables and 23 references