International guidelines promote screening by faecal tests in asymptomatic individuals at average risk of colorectal cancer (CRC), but uptake does not reach recommended levels in most countries. The aim of this study was to synthetize evidence on (a) interventions aiming to increase uptake of faecal tests for CRC screening, in asymptomatic individuals at average risk of CRC, (b) interventions that targeted general practitioner (GP) involvement and (c) interventions that targeted nonresponders or disadvantaged groups. A systematic review of randomized-controlled trials, searching PubMed, Embase and the Cochrane Library database, based on the Cochrane's Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols 2015 guidelines was performed. The risk of bias of included trials was assessed. From 24 included RCTs, the following interventions increase uptake of faecal tests: advance notification letter (OR 1.20-1.51), postal mailing (OR 1.31-7.70), telephone contacts with an advisor (OR 1.36-7.72). Three interventions showed positive effects of GP involvement such as a GP-signed invitation letter [odds ratio (OR)=1.26], GP communication training (OR=1.22) or mailing reminders to GPs (OR=14.8). Inconclusive results were found for studies comparing different types of faecal tests and those testing the effectiveness of providing various types of written information. Advance notification letters, postal mailing of the faecal tests, written reminders and telephone contacts with an advisor increase patient uptake of faecal tests. There was only limited evidence on the effect of GP involvement on screening test uptake and a lack of studies focusing on nonresponders or disadvantaged groups.