OBJECTIVES Although more than 9,000 physicians are certified to prescribe buprenorphine for opioid dependence (OD), many patients are unsuccessful in accessing outpatient OD treatment. Efforts to improve access to office-based opioid treatment (OBOT) have focused primarily on physician reimbursement or education. To our knowledge, none have directly queried physicians about factors they view as limitations to treating more OBOT patients. The goal of this study was to understand the reasons why some providers choose to maintain OBOT patient caseloads below capacity. METHODS In June 2007, a mail-based, 41-item survey to measure physician attitudes, beliefs, and experiences in chronic disease, addiction, and OD was sent to a national sample of 621 managed behavioral healthcare network physicians certified to prescribe buprenorphine. Respondents rated the degree to which 11 different scenarios independently affect their decision to use OBOT or to increase the number of OD patients they treat. Results are reported in terms of physician endorsement (i.e. the extent to which each of 11 situations influences treatment decisions). The primary outcomes measure was the number of OD patients that physicians treat with OBOT. RESULTS The response rate was 47.6% (296 physicians). The five most commonly endorsed barriers were concerns about coordinating logistics like urine tests (51.3%); attracting opioid-dependent patients to their practice (50.0%); patients selling buprenorphine or taking more than prescribed (48.4%); being available 24/7 for OBOT patients (48.3%); and ability to send challenging patients to appropriate treatment programs (42.9%). CONCLUSIONS Managed Care Organizations can improve access to OBOT by providing network physicians with logistical guidance and office management resources, such as lab testing kits, key opinion leadership, and referrals to local treatment centers.