Glass-ceramics based on hypo-eutectic (GC1) and hyper-eutectic (GC2) compositions of the Wollastonite (W, CaSiO3) - Tricalcium Phosphate [TCP, Ca3(PO4)2] binary system, which are saturated with SiO2 during the glass melting stage, are synthesized by the petrurgic method, using cooling rates of 0.5, 1 or 2°C/h. All synthesized materials are subjected to in vitro bioactivity tests using Kokubo's Simulated Body Fluid (SBF). Primary a-Cristobalite is formed in all cases. Metastable Apatite [Ap, Ca10(PO4)6O] and W phases are additionally formed, in general, in the GC1 glass-ceramics, as well as in the GC2 material obtained at a cooling rate of 0.5°C/h. However, at faster cooling rates, TCP is formed instead of Ap phase in the latter composition. During the bioactivity tests, a hydroxyapatite [HAp, Ca10(PO4)6(OH)2]-like surface layer is formed in all materials. It is proposed that GC2 glass-ceramics cooled at a rate of 1°C/h have the potential to show good in vivo osseointegration properties.