The aim of this study was to investigate of te effects of different doses gentamicin and erythromycin on spontaneous and oxytocin-induced myometrium contractions in rats. The frequency of spontaneous contractions was founded 8.22/10 min and peak amplitude was founded 2.9 g . The frequency and peak amplitude of spontanaeous contractions were dose-dependly inhibited by 0.015 mg/ml, 0.030 mg/ml and 0.062 mg/ml levels of gentamicin and 1.11(p<0.001) and 0.70 (p<0.001) respectively. The frequency and peak amplitude was founded 11.6/10 min and 3.54g respectively after 0.01 mM oxytocin-induced of myometrial samples. Both frequency and peak amplitude of oxytocin-induced myometrial contractions was decreased dose dependly the freguency 0.062 mg/ml, 0.125 mg/ml and 0.250 mg/ml doses of gentamicin and 0.40 (p<0.001) and 0.20 (p<0.001) respectively. The frequency increased and decreased and the peak amplitude was decreased after 0.6 mM, 1.2 mM and 1.8 mM doses of erythromycin added to spontaneous contractions myometrium. The frequency oxytocin-induced contractions were increased by 0.6 mM, 1.2 mM, 1.8 mM levels of erythromycin and decreased (p<0.001) by 2.4 mM erythromycin, the peaek amplitude was decreased (p<0.001) dose-depended. In conclusion, it was found that gentamicin inibited frequency and peak amplitude both of oxytocin-induced and spontaneous contractions whereas erythromycin in low doses innhibited peak amplitude of contractions but increase frequency, high doses erythromycin inhibited both amplitude and frequency of oxytocin induced and spontaneous contractions of myometrium obtained from rats.