Background: Pharmaceuticals make an important contribution to people's health. Medicines, however, are frequently not used appropriately. Improving the use of medicines can improve health outcomes and save resources. On the other hand, regulatory and educational policies may have unintended effects on health and costs., Objectives: To assess the effects of pharmaceutical educational and regulatory policies targeting prescribers on medicine use, healthcare utilisation, health outcomes and costs (expenditures)., Search Methods: We searched CENTRAL, MEDLINE, Embase, and two trial registries in March 2018 and several other databases between 2014 and 2018. We reviewed the reference lists of included studies and other relevant reviews, contacted authors of relevant reviews and studies to identify additional studies, and did a citation search for all included studies using ISI Web of Science (searched 05 January 2016)., Selection Criteria: Randomised trials, non-randomised trials, interrupted time series studies, repeated measures studies and controlled before‒after studies of policies regulating who can prescribe medicines and other policies targeted at prescribers. We included in this category monitoring and enforcement of restrictions, generic prescribing, programmes to implement treatment guidelines, system-wide policies regarding monitoring medicine safety, and legislated or mandatory continuing education or quality improvement specifically targeted at prescribing. We defined 'policies' in this review as laws, rules, financial and administrative orders made by governments, non-governmental organisations or private insurers. We excluded interventions applied at the level of a single facility. For us to include a study, it had to include an objective measure of at least one of the following outcomes: medicine use, healthcare utilization, health outcomes, or costs., Data Collection and Analysis: Two review authors independently reviewed abstracts and reference lists of relevant reports, assessed full-text studies for inclusion, extracted data, and assessed risk of bias and certainty of the evidence (GRADE). For all the steps in the above process we resolved disagreements by discussion., Main Results: We identified two studies that met our selection criteria: a controlled interrupted time series study evaluating a regulatory policy involving the monitoring of prescribing of benzodiazepines; and a controlled before‒after study of an educational policing involving mailed educational materials on prescribing for physicians and Health Maintenance Organization (HMO) members as well as an intervention to regulate drug reimbursement. We are uncertain about the effects on medicine use of a regulatory policy involving the monitoring of prescribing with triplicate prescriptions, compared with no regulatory intervention (very low certainty evidence). We are also uncertain about the effects on medicine use, assessed through doctors' prescribing, and costs of an educational policy involving mailed educational materials on prescribing for physicians and HMO members, compared to no educational intervention or an intervention to regulate drug reimbursement (very low certainty evidence). Neither of the included studies measured healthcare utilization, health outcomes, or additional costs, if any, to patients., Authors' Conclusions: We are uncertain of the effects of educational or regulatory policies targeting prescribers due to very limited evidence of very low certainty. The impacts of these policies therefore need to be evaluated rigorously using appropriate study designs. Evaluations are needed across a range of settings, including low- and middle-income countries, and across different types of prescribers and medicines., (Copyright © 2019 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.)