The development of phosphate glasses for use in orthopaedic implants has attracted much interest because their chemical and physical properties make them suitable for use as bone-bonding materials. We prepared various compositions of CaO-P2O5-MO or CaO-P2O5-M2O (M: K, Li, Na, Mg, Zn) glasses to measure ion release, solubility and bioactivity. The compositions with (Ca,M)/P molar ratio 0.6 were fixed P2O5 mol% content at 45.45 mol%, and varying MO or M2O mol% at 10, 20 and 30 mol%. Ca2+ ion release properties were investigated in 0.1M potassium acetate with pH 6 at 37oC by immersing 50 mg of powder into 100 ml of acidic buffer solution. The highest and lowest extent of released Ca2+ ion was observed for composition with 10 mol% of K2O and 30 mol% of MgO, respectively. The weight loss in distilled water at 37oC was measured. Solubility increased with decreasing CaO content, but decreased with increasing MgO content. Bioactivity in the simulated body fluid at 37oC was measured.