Objective: To evaluate the remineralizing effects of aqueous phosphate-buffered solutions using various saturations with respect to octacalcium phosphate or brushite (OCP/DCPD) on bovine enamel subsurface lesions. Method and Materials: Demineralized specimens (n = 18 per group) were exposed to one of six phosphate-buffered solutions with theoretical OCP saturations of S0.83, S1.17, S1.43, S1.64, S1.83, or S1.99 (pH, 6.3; calcium concentration, 0.53 to 3.18 mM). One aqueous solution without calcium was used as a negative control (S0; pH, 6.3); one without calcium and phosphate was a reference (S; pH, 4.3). HEPES-buffered Buskes solution served as a reference (B2.46; pH, 7.0); a pH-adjusted one was a positive control (B1.21; pH, 6.3). Mineral losses (whole lesion and surface area/inner part of the lesion) before and after storage (2 and 5 weeks, 37°C) were evaluated from microradiographs. Results: The pH values of all solutions remained stable. Compared to baseline, S0.83 to S1.99 and B2.46 to B1.21 showed significantly increased mineral gains after both storage periods (P .05, paired t test). S0 showed neutral effects (P = .190), whereas S demineralized the specimens (P .001). Storage in S1.64, S1.83, and S1.99 revealed no differences compared to B2.46 (P > .997, ANOVA and Tukey), but a mineral gain of S1.64 to S1.99 was significantly increased compared to B1.21 (P .012). Similar results could be observed for surface areas and inner lesion parts. Conclusion: The in vitro conditions chosen revealed that the used phosphate buffer system was suitable to maintain stable pH values. The higher saturated (OCP) solutions S1.64, S1.83, and S1.99 revealed mineral gains comparable to B2.46; thus, saturations of 1.64 (OCP) or 1 (DCPD) might be preferable for remineralization studies. Keywords: calcium phosphates, enamel subsurface lesion, HEPES, microradiography, phosphate buffer, remineralization, saturation