To systematically review patient-reported barriers and facilitators to shared decision making (SDM) and develop a taxonomy of patient-reported barriers. Systematic review and thematic synthesis. Study findings/results for each included paper were extracted verbatim and entered into qualitative software for inductive analysis. Electronic and follow-up searches yielded 2956 unique references; 289 full-text articles were retrieved, of which 45 articles from 44 unique studies met inclusion criteria. Key descriptive themes were grouped under two broad analytical themes: how the healthcare system is organized (4 descriptive themes) and what happens during the decision-making interaction (4 descriptive themes, 10 sub-themes). Predominant emergent themes related to patients' knowledge and the power imbalance in the doctor-patient relationship. Patients need knowledge and power to participate in SDM - knowledge alone is insufficient and power is more difficult to attain. Many barriers are potentially modifiable, and can be addressed by attitudinal changes at the levels of patient, clinician/healthcare team, and the organization. The results support the view that many patients currently can't participate in SDM, rather than they won't participate because they do not want to. Future implementation efforts should address patient-reported factors together with known clinician-reported barriers and the wider organizational context. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.