The random breath testing program in Western Australia increased in intensity over the two years October 1994 to September 1996, particularly with the introduction of two "booze buses" in the metropolitan area of Perth and more intense public education campaigns. The large number of tests carried out resulted in an increased number of charges for drink driving. A community survey showed that the program has strong support. There were positive changes in driver perceptions of the likelihood of being breath tested and of self-reported driving after drinking. There were large increases in the percentage of drivers experiencing random breath testing. Little change was observed in numbers of alcohol related crashes, the reasons for this are explored.