The effect of concurrent attendance of two inhibitors of bone degradation,namely Alendronate (Ald) sodium trihydrate and Strontium (Sr),on Calcium Phosphate Cement (CPC) characteristics was explored.To this aim,5 wt％ Strontium and 21 mM Alendronate sodium trihydrate were used in calcium phosphate cement and setting time,ion and drug release were analyzed.RAW264.7 and G cell were cultured on cement samples and Tartrate-Resistant Acid Phosphatase (TRAP),Alkaline phosphatase (ALP) activity and MTT assay were studied.The results of structural analysis indicated that 21 mM Ald did not let the cement set.Therefore,colloidal silica was added to the cement formula and successfully decreased the setting time.In vitro tests showed Sr-loaded sample had a greater inhibitory effect on biocompatibility of G cells than Ald-loaded and Sr-Ald-loaded samples.In addition,the findings about osteoblast MTT and ALP activity indicated that Sr was more effective in osteogenic activity of G cells.The simultaneous presence of Ald and Sr in Calcium Phosphate Cement (CPC) was not as effective in its biocompatibility as the presence of Sr alone.