Educational outreach visits (EOVs) are face-to-face visits by trained individuals to healthcare professionals to improve their practice. This review assessed the effects of EOVs on health professional practice and healthcare outcomes. A total of 69 studies involving over 15,000 health professionals were included. The median adjusted risk difference (RD) in compliance with desired practice was 5.6% (interquartile range 3.0% to 9.0%). For prescribing, the adjusted RD was 4.8% (interquartile range 3.0% to 6.5%). For other professional performances, the adjusted RD was 6.0% (interquartile range 3.6% to 16.0%). Meta-regression did not provide compelling explanations for the observed variation in adjusted RDs. For continuous outcomes, the median adjusted relative improvement was 21% (interquartile range 11% to 41%). Interventions that included EOVs appeared slightly superior to audit and feedback. Only six studies evaluated different types of visits in head-to-head comparisons. When individual visits were compared to group visits, the results were mixed. EOVs alone or when combined with other interventions had relatively consistent and small effects on prescribing, but effects on other types of professional performance varied. The review found that EOVs can be effective in improving practice in most circumstances, but the effect is variable. The median adjusted RD for dichotomous outcomes was 5.6%, and for continuous outcomes, there was at least a 20% relative improvement in about half of the 20 comparisons. The findings are similar to those reported by others, with a median adjusted RD of 5% for EOVs combined with other interventions. The review suggests that interventions such as EOVs, audit and feedback, or local opinion leaders can lead to absolute improvements in practice of five to ten percent. None of the variables hypothesized to explain the variance in effects were statistically significant.Educational outreach visits (EOVs) are face-to-face visits by trained individuals to healthcare professionals to improve their practice. This review assessed the effects of EOVs on health professional practice and healthcare outcomes. A total of 69 studies involving over 15,000 health professionals were included. The median adjusted risk difference (RD) in compliance with desired practice was 5.6% (interquartile range 3.0% to 9.0%). For prescribing, the adjusted RD was 4.8% (interquartile range 3.0% to 6.5%). For other professional performances, the adjusted RD was 6.0% (interquartile range 3.6% to 16.0%). Meta-regression did not provide compelling explanations for the observed variation in adjusted RDs. For continuous outcomes, the median adjusted relative improvement was 21% (interquartile range 11% to 41%). Interventions that included EOVs appeared slightly superior to audit and feedback. Only six studies evaluated different types of visits in head-to-head comparisons. When individual visits were compared to group visits, the results were mixed. EOVs alone or when combined with other interventions had relatively consistent and small effects on prescribing, but effects on other types of professional performance varied. The review found that EOVs can be effective in improving practice in most circumstances, but the effect is variable. The median adjusted RD for dichotomous outcomes was 5.6%, and for continuous outcomes, there was at least a 20% relative improvement in about half of the 20 comparisons. The findings are similar to those reported by others, with a median adjusted RD of 5% for EOVs combined with other interventions. The review suggests that interventions such as EOVs, audit and feedback, or local opinion leaders can lead to absolute improvements in practice of five to ten percent. None of the variables hypothesized to explain the variance in effects were statistically significant.