Objective To compare the effectiveness and safety of repeat misoprostol versus expectant management in women with first‐trimester incomplete miscarriage who have been initially treated with misoprostol. Methods The study was an open‐labeled randomized controlled trial including women with an incomplete first‐trimester miscarriage after administration of misoprostol. The participants were randomly assigned to vaginal misoprostol or expectant management using a computer‐generated table of random numbers. The primary outcome was the number of women with a complete miscarriage at 1 week. Results Eighty‐eight women (44 women in each group) were analyzed. The rate of complete miscarriage at 1 week was significantly higher in the misoprostol group than the expectant management group—29 (69.0%) versus 7 (16.7%) (P < 0.001), respectively. Women in the misoprostol group were more satisfied (7.00 ± 0.77 vs 4.57 ± 1.61, P < 0.001) but reported more pain (7.95 ± 1.85 vs 5.26 ± 1.08, P < 0.001) than women in the expectant group. The misoprostol group reported more adverse effects than the expectant management group (P < 0.001). Conclusion In women with an incomplete first‐trimester miscarriage who were initially treated with misoprostol, repeat administration of misoprostol was more effective than expectant management for achieving complete miscarriage at 1 week. However, misoprostol was associated with more adverse effects. Registration site and number Clinicaltrials.gov: NCT03148561.