Oral pre-exposure prophylaxis (PrEP) can reduce HIV incidence among at-risk persons. However, for PrEP to have an impact in decreasing HIV incidence, clinicians will need to be willing to prescribe PrEP. HIV specialists are experienced in using antiretroviral medications, and could readily provide PrEP, but may not care for HIV-uninfected patients. Six focus groups with 39 Boston area HIV care providers were conducted (May-June 2012) to assess perceived barriers and facilitators to prescribing PrEP. Participants articulated logistical and theoretical barriers, such as concerns about PrEP effectiveness in real-world settings, potential unintended consequences (e.g., risk disinhibition and medication toxicity), and a belief that PrEP provision would be more feasible in primary care clinics. They identified several facilitators to prescribing PrEP, including patient motivation and normative guidelines. Overall, participants reported limited prescribing intentions. Without interventions to address HIV providers' concerns, implementation of PrEP in HIV clinics may be limited.