The publication of the DSM-IV represents the first revision in 7 years to the DSM-III-R diagnostic criteria. The purpose of the current study is to evaluate the impact of changes to the Axis II criteria on diagnostic rates in a substance abusing population. We interviewed 370 patients entering treatment using a modified version of the SCID-II, which allowed for the diagnosis of both DSM-III-R and DSM-IV Axis II diagnoses. Prevalence rates for each Axis II disorder are given, as well as kappa statistics showing diagnostic agreement between the two systems. The results of this study indicate good rates of diagnostic agreement between the two systems with a few notable exceptions. Poor rates of diagnostic agreement were obtained for the histrionic and dependent diagnostic categories. No single diagnostic change appears to be responsible for the prevalence rate differences between the two systems.