The primary aim of this study was to evaluate the effect of oral dydrogesterone on the recurrent uterine contraction in preterm labor. The secondary aims were to evaluate latency period, gestational age at delivery, pregnancy outcomes, neonatal outcomes, compliance and side effects. A randomized, double blinded, placebo controlled trial was conducted. Forty-eight pregnant women at 24-34 weeks gestation with preterm labor were either randomized to study group receiving tocolytic treatment combined with oral dydrogesterone (20 mg daily) or to placebo group receiving tocolytic treatment combined with oral placebo. Recurrent rates of uterine contraction were comparable between groups (87.5% vs 91.7%, p = 0.64). Latency periods were not different between dydrogesterone and placebo group (32.7 ± 20.2 days vs 38.2 ± 24.2 days, p = 0.39). There were also no differences in gestational age at delivery, pregnancy outcomes, neonatal outcomes, compliance and side effects. Adjuvant treatment with oral dydrogesterone 20 mg/day could not decrease the rates of recurrent uterine contraction and prolong latency period in preterm labor management when compared to placebo.