BackgroundA key function of health systems is implementing interventions to improve health, but coverage of essential health interventions remains low in low-income countries. Implementing interventions can be challenging, particularly if it entails complex changes in clinical routines; in collaborative patterns among different healthcare providers and disciplines; in the behaviour of providers, patients or other stakeholders; or in the organisation of care. Decision-makers may use a range of strategies to implement health interventions, and these choices should be based on evidence of the strategies' effectiveness.ObjectivesTo provide an overview of the available evidence from up-to-date systematic reviews about the effects of implementation strategies for health systems in low-income countries. Secondary objectives include identifying needs and priorities for future evaluations and systematic reviews on alternative implementation strategies and informing refinements of the framework for implementation strategies presented in the overview.MethodsWe searched Health Systems Evidence in November 2010 and PDQ-Evidence up to December 2016 for systematic reviews. We did not apply any date, language or publication status limitations in the searches. We included well-conducted systematic reviews of studies that assessed the effects of implementation strategies on professional practice and patient outcomes and that were published after April 2005. We excluded reviews with limitations important enough to compromise the reliability of the review findings. Two overview authors independently screened reviews, extracted data and assessed the certainty of evidence using GRADE. We prepared SUPPORT Summaries for eligible reviews, including key messages, 'Summary of findings' tables (using GRADE to assess the certainty of the evidence) and assessments of the relevance of findings to low-income countries.Main resultsWe identified 7272 systematic reviews and included 39 of them in this overview. An additional four reviews provided supplementary information. Of the 39 reviews, 32 had only minor limitations and 7 had important methodological limitations. Most studies in the reviews were from high-income countries. There were no studies from low-income countries in eight reviews.Implementation strategies addressed in the reviews were grouped into four categories – strategies targeting:1. healthcare organisations (e.g. strategies to change organisational culture; 1 review);2. healthcare workers by type of intervention (e.g. printed educational materials; 14 reviews);3. healthcare workers to address a specific problem (e.g. unnecessary antibiotic prescription; 9 reviews);4. healthcare recipients (e.g. medication adherence; 15 reviews).Overall, we found the following interventions to have desirable effects on at least one outcome with moderate- or high-certainty evidence and no moderate- or high-certainty evidence of undesirable effects.1.Strategies targeted at healthcare workers: educational meetings, nutrition training of health worker...