Objectives The aim of this in vitro study was to compare the remineralizing effect of three rinses: (A) 0.17% sodium monofluorphosphate and 0.05% calcium glycerophosphate (220 ppm fluoride), (B) 0.05% sodium fluoride (220 ppm fluoride) and (C) control mouthrinse (without fluoride or calcium). Method and Materials Demineralized areas were created in 90 pieces of bovine enamel by submerging them in an acid solution (pH 4.4) for 48 hours. Part of the surface was painted with nail varnish to preserve the demineralized area and the specimens were assigned at random to three groups. The specimens were stored in artificial saliva at pH 7 and 37ºC for 30 days. Twice daily they were immersed for 60 seconds in the respective mouthrinse. Following the experimental period, the specimens were bisected and examined by scanning electron microscopy. Results The mean percentage of remineralization produced by the mouthrinses was as follows: (A) 54.08 (95% CI 46.37- 61.78), (B) 38.43 (95% CI 30.89-45.98) and (C) 30.18 (95% CI 25.56-34.80). The differences between the three groups were statistically significant. Conclusion The results show that the fluoride and calcium mouthrinse has a significantly greater remineralizing capacity than the fluoride mouthrinse with the same fluoride ion concentration under the in vitro conditions of this study.