This study examined the prevalence of driving under the influence of cannabis (DUIC), and DUIC and alcohol together, in an area of Australia with a high number of young cannabis users. A telephone survey of 502 18-29 year olds on the North Coast of New South Wales revealed that, overall, 11.2 per cent of respondents had ever driven within an hour of using cannabis, and 7.4 per cent had done so in the previous 12 months. Among recent cannabis users, 43.1 per cent had ever driven within an hour of using cannabis and 28.5 per cent had done so in the previous 12 months. Among those who reported using cannabis weekly or more frequently in the previous 12 month, 53.8 per cent reported having driven under the influence of cannabis in their lifetime and 40.6 per cent reported this behaviour in the previous 12 months. While only 1.8 per cent of the sample had driven within an hour of using both cannabis and alcohol together in the previous 12 months, this constituted 6.9 per cent of all recent cannabis users, and 24.3 per cent of those who had driven under the influence of cannabis in the previous 12 months. The prevalence of DUIC alone, and in combination with alcohol, appears to be low among the population, but higher among those who regularly use cannabis. Results are discussed in terms of their implications for public health and education campaigns.