The aim of this study was to evaluate the ability of calcium phosphate and fluoride containing varnishes to inhibit enamel demineralization. Six varnishes were selected for analysis: (1) Enamel Pro containing amorphous calcium phosphate; (2) Clinpro White containing functionalized tricalcium phosphate (fTCP); (3) MI Varnish containing casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP); (4) Duraphat (first no added calcium control); (5) Profluorid (second no added calcium control); and (6) placebo (no added calcium or fluoride control). Human enamel slabs (36) were each cut into half-slabs and covered with one of the six dental varnishes to create a window. The half-slabs were then individually immersed in a polyacrylate demineralization buffer pH 4.8 for four days at 37 °C with a change of solution each day. Mineral content was determined using transverse microradiography. All fluoride-containing varnishes significantly inhibited enamel demineralization when compared with the placebo varnish. However, out of the calcium phosphate and fluoride containing varnishes only MI Varnish, containing fluoride and CPP-ACP was superior to the fluoride-alone varnishes. MI Varnish also released the highest levels of calcium, phosphate and fluoride ions. MI Varnish containing fluoride and CPP-ACP was superior to the other varnishes in protecting against enamel demineralization.