The cariostatic effect of local application of fluoride was first demonstrated with fluoride-containing water and fluoride painting, initiating studies on fluoride-mouthrinses. The 1st trials with acidulated solutions were negative, but positive results were recorded in Goteborg, Sweden, following rinses with neutral NaF solutions on children. The mouth-rinsing procedure is simple, efficient and a valuable mass prophylactic routine in low-fluoride areas. Fluoride rinses have been clinically evaluated under a variety of conditions and with different results. To partly explain the variability of the results, the reported studies are grouped according to design of trials and age of subjects. On the basis of the controlled trials and the long-term studies, cost and efficiency of the fluoride rinses are estimated.