We assessed the quality of care for substance use disorders (SUDs) among 8,083 patients diagnosed with serious mental illness from the VA mid-Atlantic region. Using data from the National Patient Care Database (2001-2002), we assessed the percentage of patients receiving a diagnosis of SUD, percentage beginning SUD treatment 14 days or earlier after diagnosis, and percentage receiving continued SUD care 30 days or less. Overall, 1,559 (19.3%) were diagnosed with an SUD. Of the 1,559, 966 (62.0%) initiated treatment and 847 (54.3%) received continued care. Although patients diagnosed with bipolar disorder were more likely to receive a diagnosis of SUD than those diagnosed with schizophrenia or schizoaffective disorder (22.7%, 18.9%, and 17.7%, respectively; chi(2) = 26.02, df = 2, p < .001), they were less likely to initiate (49.1%, 70.7%, and 68.6%, respectively; chi(2) = 59.29, df = 2, p < .001) or continue treatment (39.9%, 63.2%, and 62.2%, respectively; chi(2) = 72.25, df = 2, p < .001). Greater efforts are needed to diagnose and treat SUDs in patients with serious mental illness, particularly for those with bipolar disorder. (c) 2006 Elsevier Inc. All rights reserved.