Until 2003, all random breath testing (RBT) in South Australia was conducted in the ‘static’ mode, which involves a highly visible random breath testing station set up by the side of the road where police flag down drivers and test them. In 2003, police in South Australia were given the right to operate RBT in the ‘mobile’ mode. This involves the drivers of mobile police vehicles stopping motorists at random and breath testing them, and enables the patrolling of minor roads and detecting drink drivers who may be using them to escape RBT stations. Initially, mobile RBT was only legislated to operate in ‘prescribed periods’, which included long weekends, school holidays and four other periods during the year that did not exceed 48 hours. In mid-2005, legislation was passed to allow mobile RBT to be conducted on a full-time basis. The objective of this paper is to provide an indication of the relative detection rates of mobile and traditional static RBT in South Australia, using the most recent available data (from 2004). Additionally, South Australian mobile RBT operations will be compared with those of other Australian states in which mobile RBT has been operating for a longer time. Data for 2004 RBT operations were provided by the Traffic Intelligence Section of the South Australian Police. Similar sections of the police force in other states were contacted to obtain interstate RBT data for comparison. In 2004, there were 653,333 random breath tests conducted in South Australia, 46,030 of which were done using mobile RBT (7.0%). A comparison with other states indicates that, in 2004, South Australia conducted a lower percentage of its RBT tests using the mobile mode. The percentage of tests conducted using mobile RBT in the four other states for which data were available ranged between 21.5 (New South Wales) and 78.5 (Tasmania). With regard to detection rates, mobile operations detected drink drivers at a rate of six times that detected using static mode RBT. In rural areas, the advantage of mobile RBT was more pronounced, with a detection rate 11 times that of static RBT. A higher detection rate with mobile RBT occurred regardless of the time of day of testing. Interstate comparisons suggested that drink driving detections per head of population were higher in states conducting a greater number of random breath tests and conducting a greater percentage of their tests using mobile RBT. Mobile RBT provides a means of detecting drink drivers at a higher rate than is achievable using the more traditional static RBT. It is recommended that more emphasis be given to mobile RBT in South Australia than was the case in 2004. This would be likely to lead to a greater number of detections for drink driving and greater ‘specific deterrence’. However, it is still important to operate high visibility static RBT to maintain ‘general deterrence’ of drink driving.