Data sourcesPubMed, the Cochrane Library, Centre for Reviews and Dissemination (CRD) and Embase.Data abstraction and synthesisTwo independent reviewers selected studies, abstracted data and assessed study quality using the GRADE criteria. Meta-analysis was conducted using a random effects model.Study selectionRandomised controlled trials including in situ studies.ResultsSeven studies were included, five conducted in children and two in adults. The two adult studies and one child study were considered to be at high risk of bias. The remaining four child studies were considered to be at moderate risk of bias. These four studies compared 1450ppm fluoride toothpaste with 1.5% arginine against 1450ppm fluoride toothpaste as a control. Meta-analysis of three studies showed a positive effect on caries measured using quantitative light-induced fluorescence (QLF) in favour of arginine; mean difference -4.67, (95%CI, -6.34 to -3.01). The overall GRADE assessment of this was considered to be very low.ConclusionAt present there is insufficient evidence in support of a caries-preventive effect for the inclusion of arginine in toothpastes. More rigorous studies, and studies which are less dependent on commercial interests, are required.