1) Introduction: The combination between high power lasers and fluoride may potentially control the progression of dentin erosion. Therefore, the aim of this study was to evaluate the effect of Er,CrYSGG laser, associated to fluoride application, in the control of dentin erosion. 2) Materials and Methods: Dentin slabs were embedded into acrylic resin, flattened and polished. The specimens (n=10) were previously eroded (10min immersion in 1% citric acid solution) and randomly allocated into the experimental groups, according to the following treatments: control (no treatment); acidulated phosphate fluoride (APF) gel (1.23% F, 1min); Er,Cr:YSGG laser irradiation (parameter 1: 0.25W, 20Hz, 2.8J/cm2); Er,Cr:YSGG loser irradiation (parameter 2: 0.50W, 20Hz, 5.7J/cm2); APF gel+Er,Cr:YSGG laser parameter 1 and; APF gel+Er,Cr:YSGG laser parameter 2. After, they underwent on erosion-remineralization cycling, consisting of a 5min immersion into 0.3% citric acid, followed by 60min exposure to artificial saliva. This procedure was repeated 4x/day, for 5 days. Surface loss (SL, in ??m) was determined with optical profilometry. The specimens were analyzed by environmental scanning electron microscopy (n=3). Data were statistically analyzed (??=0.05). 3) Results: None of the groups significantly differed from the control group, except for the APF group. APF gel presented the lowest SL, not differing from Er,Cr.YSGG laser (parameter 1) and APF gel+Er,Cr:YSGG laser (parameter 1). Selective structure removal was observed for the laser-treated groups. 4) Conclusions: None of the Er,Cr:YSGG laser parameters were effective in the control of dentin erosion. The laser was also not able to enhance the protection of fluoride against dental erosion.