In vitro and in vivo studies have proven strontium to be an osteoinductive trace element. The effect of strontium ranelate (SR) on H2O2-induced apoptosis of CRL-11372 cells and optimization of its anti-apoptotic dose were the aims of this study. After 1 h of pretreatment with SR 1 mu M, 50 mu M, 100 mu M, 500 mu M, and 1,000 mu M concentrations, CRL-11372 osteoblasts were exposed to 100 mu M H2O2 for periods of 6-12 h. The same experiments were repeated without H2O2. The apoptotic index and viability of cells were assessed quantitatively with a fluorescent dye and qualitatively with agarose gel electrophoresis. Concentrations of 1-100 mu M of SR with a 6-h treatment and only 1 mu M concentration with a 12-h treatment inhibited the apoptotic effect of H2O2 on cultured osteoblasts significantly (P < 0.05). SR was shown to inhibit H2O2-induced apoptosis of CRL-11372 cells in a dose-dependent manner.