The high range PCA is considered 0.15 grams per 100 milliliters or greater; this is three times the legal limit of 0.05 blood alcohol concentration (BAC). The crash risk associated with a BAC of 0.15 is 25 times that associated with a zero BAC. The New South Wales Roads and Traffic authority (RTA) provided data for this study from its Driver and Vehicle Systems (DRIVES) database, which includes traffic convictions. For the purposes of this study, a prior PCA conviction meant a prior conviction in the current or previous 5 fiscal years. The data used in this study pertained to the cases processed in the 5 years ending June 30, 1997-2001. Each case was a high-range PCA offender (n=28,666). The analysis of these cases first determined the PCA offending history of each annual cohort of DUI offenders. It then examined the penalties imposed on high-range PCA offenders. This was followed by a calculation of the probability of imprisonment for high-range PCA offenders across a number of demographic and conviction factors. A multivariate logistic regression approach was then used to estimate the impact of PCA offending history on the imprisonment rate for high-range PCA offenders, controlling for a range of influential demographic and conviction variables. The study found that for offenders convicted of high-range PCA offenses over the study period, almost 25 percent were repeat DUI drivers. Of these repeat offenders, just over half had a prior conviction for an offense that involved a high-range PCA. The probability of imprisonment for a male DUI offender aged 25-49 with no prior or concurrent DUI conviction was less than 1 percent. The probability of imprisonment increased to about 76 percent when the offender had three or more prior DUI convictions and a concurrent driving conviction. Offenders who had a prior high-range PCA conviction were more likely to be imprisoned than those who had only a low-range PCA conviction. Males who had more than one prior high-range PCA conviction were more likely to be imprisoned than those who had only one. There were insufficient numbers of cases in the final model to consider the equivalent effect for females. 8 tables, 5 figures, and 9 notes