There is considerable debate in Australia concerning the effects of cannabis on driving and whether it has a causal role in traffic accidents. Although there is some evidence showing that cannabis impairs psychomotor performance, epidemiological studies suggest that there is no significant increase in accident risk associated with the use of cannabis alone. Cannabis used with alcohol however does appear to significantly increase accident risk. Whilst survey research has documented the proportion of people, particularly younger people, who use cannabis, there are few reports examining the frequency with which people drive while affected by cannabis. Sixty-seven cannabis users in Melbourne were surveyed and questioned at length about their patterns of cannabis and alcohol use and driving, and their attitudes regarding driving while intoxicated. Sixty percent of these participants use cannabis at least once every two days. These participants drive more frequently after using cannabis alone than after using cannabis with alcohol. In terms of the effects of these drugs on driving skills, these participants believe that cannabis with alcohol is much more dangerous than cannabis alone. The findings from this study are discussed in relation to legislative changes around cannabis and driving planned for Victoria, Australia.