BACKGROUND: As clozapine is under-prescribed in persons with treatment-resistant schizophrenia (TRS), it is necessary to better identify the determinants of health inequalities in access to clozapine use. OBJECTIVE: To identify mental health professionals' characteristics or attitudes and institutional characteristics facilitating or limiting clozapine prescribing. METHOD: We systematically searched multiple electronic databases for articles reporting: (i) mental health professionals' attitudes and characteristics favoring or limiting clozapine prescribing; (ii) institutional characteristics associated with variations in clozapine prescribing; (iii) interventions aimed at enhancing clozapine prescribing. Data were synthesized narratively. RESULTS: A total of 31 articles reporting findings of 29 studies published from 1993 to 2017 in 11 countries fulfilled our inclusion criteria. The main prescriber-related barriers to clozapine prescribing are lack of personal prescribing experience and concern with pharmacological characteristics of clozapine (blood monitoring and adverse effects). Lack of knowledge about the effectiveness of clozapine does not appear as a major determinant of under-prescription. Institutional-related characteristics favoring clozapine prescribing are prescribers' adherence to evidence-based medicine principles and learning by modelling from experienced clozapine prescribers. CONCLUSION: Effective strategies to increase access to clozapine in persons with TRS include implementation of integrated clozapine clinics, simplification of blood monitoring, education for prescribers and contact with experienced prescribers. Programs addressing barriers in clozapine prescription need to be disseminated more broadly to ensure persons with TRS have access to evidenced based treatments such as clozapine. Inequality in access to clozapine care should be more systematically handled by mental health facilities and health regulatory agencies.< Réduire