BACKGROUND: Addressing the opioid epidemic would benefit from primary care clinicians identifying and managing opioid use disorder (OUD) during routine clinical encounters, but current rates are low. Clinical decision support (CDS) systems are a promising way to facilitate such interactions, but will clinicians use them? METHODS: We iteratively conducted semi-structured interviews with 8 purposively sampled primary care clinicians participating in a pilot OUD-CDS study to identify attitudes toward discussing OUD and preferences for support in doing so. Five of them had used a pilot version of the CDS for 6 months, while the others were in comparison clinics. Interviews were recorded, transcribed, and analyzed by a multi-disciplinary group of experienced researchers, using an editing organizing style where the analysts independently highlighted relevant text and then discussed to reach a consensus on themes. RESULTS: We identified five themes: 1. Primary care is the right place to address OUD. 2. Both clinician-patient and clinician-clinician relationships affect how and whether clinicians address OUD in a particular patient encounter. 3. The main challenges are limited time and competing priorities for these complex patients. 4. Although a CDS for OUD could be very helpful, it must meet different needs for different clinicians and clinical situations and be simple to use. 5. For optimal benefit, the CDS needs to be complemented by supportive organizational policies and systems as well as local clinician encouragement. CONCLUSIONS: With the right design and a supportive organization, these primary care clinicians believe a CDS could help them regularly identify and address OUD among their patients as long as it incorporates their concerns about relationships, competing priorities, patient complexity, and user simplicity.