Ag doped Hydroxyapatites (Ag-HAp) was prepared through either ion exchange or coprecipitation to compare the durability of antimicrobial effect. In case of ion exchanged Ag-HAp, the microbials reproliferated after 100 h, in spite of the rapid reduction of E.Coli during the initial moment. On the contrary, coprecipitated Ag-HAp effectively suppressed the reproliferation until 1000 h. The difference in durability depending on synthesis route was analysed with respect to the amount of silver released at each interval. In case of ion exchanged Ag-HAp, more than 60% of overall silver was released during initial 10 minitues. On the contrary, coprecipitated Ag-HAp released less than 40% of overall silver during the same period, meaning the comparatively uniform release behavior.