Abstract Background Bipolar disorder (BD) is more prevalent among people with substance use disorders (SUD) than the general population. SUD among recidivist driving under the influence (DUI) populations are extremely prevalent; not surprisingly, recent evidence suggests that rates of BD also are elevated among DUI offenders. Studies of BD patients with SUD have found high prevalence of other psychiatric disorders and relatively low rate of treatment engagement. This study examines both the prevalence of other mental disorders and treatment status among a cohort of DUI offenders with BD and SUD. Methods A consecutively selected cohort ( N = 729) of repeat DUI offenders attending a two-week inpatient treatment program completed a standardized diagnostic interview (the Composite International Diagnostic Interview: CIDI). The CIDI generated DSM-IV diagnoses. Results This study yielded three main results for this repeat DUI offender sample: (1) BD is associated with significantly higher lifetime prevalence of alcohol, drug, and non-substance psychiatric disorders (e.g., PTSD); (2) approximately one quarter of BD participants have not discussed their mania with a professional; and (3) only half of the BD participants in this cohort have had mania treatment they consider effective and even fewer have had any treatment during the past twelve months. Limitations Participants were predominantly Caucasian males attending treatment as a sentencing option in a single Massachusetts DUI program. Conclusion These findings suggest that clinicians in DUI treatment settings should consider both evaluating for BD and initiating therapy.