Drug and alcohol-related traffic accidents are a major cause of morbidity and mortality around the world. International studies have indicated that cars are a frequent injection location for injecting drug users (IDU). In Australia, cars were the third most common place for injection drug use. Such widespread use of drugs in cars presents plentiful opportunities for drug driving. A sample of 300 regular IDU’s was recruited from various areas around Sydney between April and November 2002. Participants completed structured interviews that addressed demographic information, history of drug use, current drug use, frequency of drug use, and drug injection in cars. Participants also completed the Severity of Dependence Scale and the General Health Questionnaire. Participants were asked if they had ever driven a vehicle within an hour of using drugs. Results of statistical analyses indicated that 87 percent of the IDU’s that had ever driven a vehicle, did so within an hour of injecting drugs; 88 percent of IDU drivers had done so within the past 12 months. Another 20 percent of IDU drivers had drug driven at least weekly during the preceding 12 months. No significant sex differences were noted among the drug drivers. One-third of IDU lifetime drivers reported having a drug driving accident, while 9 percent of current IDU drivers reported a drug driving accident during the past 12 months. Males were more likely than females to report lifetime drug driving accidents. The most common drugs used before driving during the preceding year were: cannabis, heroin, amphetamines, and cocaine. In terms of risk perceptions, cannabis was perceived as the least dangerous substance and alcohol was perceived as the most dangerous substance for driving performance. Finally, three main groups of risk factors were associated with drug driving: high levels of drug dependence, frequent drug use, and extensive polydrug use. The findings underscore the seriousness and prevalence of drug driving and drug-related traffic accidents. Tables, figures, references