The effect of 1.23% acidulated phosphate fluoride, 0.40% stannous fluoride gels, and 2.00% citric acid solution on 150.00 overglazed and 150 autoglazed porcelain surfaces was measured using a profilometer. Application of 1.23% acidulated phosphate fluoride for periods of 16 and 32 minutes caused etching in both groups, but the autoglazed group was significantly more effected. In both groups increase in application time did not affect the amount of etching. No etching was detected in either group after the application of 0.40% stannous fluoride for 6 and 12 hours and 2.00% citric acid for 4 and 8 hours.