The study interviewed 320 recent cannabis users in Sydney and Newcastle, from which a final sample of 120 Newcastle residents and 200 Sydney residents were selected. To be eligible for the study, participants had to be 18 years old or older, have used cannabis at least once in the previous 12 months, and have driven a motor vehicle within the previous 12 months, although not necessarily DUIC. Although much of the questionnaire used in the study elicited descriptive information on the relationship between DUIC and accident risk as well as the factors that contributed to DUIC in the previous 12 months, a special section of the questionnaire assessed the likely effect of perceived risk and perceived sanction severity on willingness to engage in DUIC. The prevention strategies posed in questionnaire scenarios were roadside drug testing (RDT), more severe penalties for DUIC, and providing factual information about the risk of accidents associated with DUIC. The findings provided only limited support for a relationship between DUIC and accident risk. RDT was apparently a more effective deterrent against DUIC than either increasing the severity of sanctions or providing factual information on the risks associated with the behavior. Those most likely to report DUIC within the past 12 months were males, dependent users, early-onset cannabis users, frequent drivers, cannabis users who had used more classes of other drugs, and cannabis users who believed that their risk of an accident would not increase following cannabis use. 6 tables, 3 figures, 58 references, appended description of scenarios, and 7 notes