Objective To investigate the effects of different concentrations of morphine in combination with ropivacaine on proliferation,migration,invasion and cell cycle in MDA-MB-231 breast cancer cells.Methods MDA-MB-231 breast cancer cells were inoculated on the culture plate for 24h and randomly divided into 8 groups:Control group(C),ropivacaine 400μg/ml group(R),morphine 3μg/ml group(LM),morphine 30μg/ml group(MM),morphine 300μg/ml group(HM),ropivacaine 400μg/ml group+ morphine 3μg/ml group(R+LM),ropivacaine 400μg/ml+ morphine 30μg/ml group(R+MM),and ropivacaine 400μg/ml+ morphine 300μg/ml group(R+HM).After treaments of MDA-MB-231 breast cancer cells for 24h,these proliferation,migration,invasion and cell cycle were evaluated.Results When using morphine alone,the proliferation inhibitive effect was positively correlated with the concentration of morphine.The proliferation was significantly inhibited by morphine of LM,MM,HM group(P<0.05).When using ropivacaine alone,the proliferation was significantly inhibited(P<0.05).When using morphine combined with ropivacaine,the high concentration morphine group has a synergistic effect with ropivacaine group on proliferation inhibition(P<0.05).When using morphine alone,the migration rate decreases sequentially with the increase of morphine concentration.The migration rate was significantly inhibited by morphine of LM,MM,HM group(P<0.05).When using ropivacaine alone,the migration rate was inhibited(P<0.05).When using morphine combined with ropivacaine,the low and medium concentration morphine group have a synergistic effect with ropivacaine group on migration rate(P<0.05).When using morphine alone,the number of cell invasion was decreased with the concentration of morphine increasing(P<0.05).The MM and HM groups inhibited cell invasion ability.When using ropivacaine alone,the invasiveness of cells was also inhibited(P<0.05).When using morphine combined with ropivacaine,the medium and high concentration morphine groups have a synergistic effect with ropivacaine group on inhibiting cell invasion ability(P<0.05).When using morphine alone,the cell cycle progression was inhibited into G2/M Phase(P<0.05).When using ropivacaine alone,the cell cycle progression was inhibited into G2/M phase(P<0.05).The combination of low concentration morphine and ropivacaine has synergistic effect on arresting at G0/G1 and S phase(P<0.05).Conclusion Morphine combined with ropivacaine inhibits the Proliferation,migration and invasion of MDA-MB-231 breast cancer cells in a dose-dependent manner.