OBJECTIVE: This study examined ethnic differences in accessing treatment for depression and substance use disorders (SUDs) among men and women in a large integrated health plan, and explored factors potentially contributing to health care disparities. METHODS: Participants were 22,543 members ages 20 to 65 who responded to health surveys in 2002 and 2005. Survey questions were linked to provider-assigned diagnoses, electronic medication, psychiatry, and chemical dependency program records. RESULTS: Among women diagnosed with depression, Latinas (p < .01) and Asian-Americans (p < .001) were less likely than Whites to fill an antidepressant prescription. Among men diagnosed with depression, African Americans (p < .01) were less likely than Whites to do so. Among women diagnosed with an SUD, African Americans (p < .05) were less likely than Whites to have one or more chemical dependency program visits. CONCLUSIONS: Results demonstrated ethnic differences in accessing depression and SUD treatment among patients diagnosed with these disorders, which persisted after controlling for education, income, having a regular health care provider and length of health plan enrollment. Findings highlight potential gender differences in ethnic disparities, lower antidepressant utilization among Asian Americans, and the effects of co-occurring disorders in accessing behavioral health care.