Bipolar patients with comorbid substance abuse or dependence (‘dual diagnosis’ patients) represent a major public health problem. Substance abuse generally predicts poor outcome and higher morbidity/mortality in bipolar disorder. For the purposes of this review, open and controlled studies of dual diagnosis assessment and treatment were located through electronic searches of several databases. Pertinent case reports were also evaluated. The results of the search were evaluated in light of the authors’ own research on dual diagnosis patients.Literature searching revealed few controlled studies to guide pharmacotherapy of bipolar patients with comorbid substance abuse or dependence. However, preliminary evidence suggests that the best outcomes are usually achieved with antiepileptic mood stabilisers and/or atypical antipsychotics, combined with appropriate psychosocial interventions. The latter may include classical 12-step groups, integrated group therapy or individual psychotherapy. While it is often difficult to determine the precise pathway to comorbid bipolar disorder/substance abuse, it is clear that both disorders must be vigorously treated. This requires a carefully integrated biopsychosocial approach, involving appropriate mood stabilisers and psychosocial interventions. Many more controlled studies of these combined treatment approaches are needed.