The high prevalence of health and psychosocial needs among methadone treatment patients has prompted efforts to supplement methadone treatment with additional services. Research has generally focused on linking supplemental service utilization to drug treatment outcomes, with fewer studies aimed at understanding supplemental service utilization itself. This study with randomly selected male methadone maintenance treatment program (MMTP) patients examined associations between sociodemographic factors and supplemental service utilization while controlling for need for services and treatment duration. Findings indicate that MMTP patients who are African American, Latino, uninsured, or have less education were less likely to report any supplemental service utilization. Hypotheses positing sociodemographic differences in regular vs. occasional service utilization were not supported. There is a need to improve access to supplemental services for minority and disadvantaged MMTP patients, and MMTPs may represent an important venue to address health disparities in general.