Objective To examine whether intrauterine application of auto-crosslinked hyaluronic acid (ACP) gel, after dilatation and curettage (D&C), reduces the incidence of intrauterine adhesions (IUAs). Design Multicenter; women and assessors blinded prospective randomized trial. Setting University and university-affiliated teaching hospitals. Patient(s) A total of 152 women with a miscarriage of <14 weeks with at least one previous D&C for miscarriage or termination of pregnancy. Intervention(s) Women were randomly assigned to either D&C plus ACP gel (intervention group) or D&C alone (control group). A follow-up diagnostic hysteroscopy was scheduled 8–12 weeks after the D&C procedure. Main Outcome Measure(s) The primary outcome was the number of women with IUAs and the secondary outcome was the severity of IUAs. Result(s) Outcomes were available for 149 women: 77 in the intervention group and 72 in the control group. The IUAs were observed in 10 (13.0%) and 22 women (30.6%), respectively (relative risk, 0.43; 95% confidence interval 0.22–0.83). Mean adhesion score and the amount of moderate-to-severe IUAs were significantly lower in the intervention group according to the American Fertility Society (AFS) and European Society of Gynecological Endoscopy classifications systems of adhesions. Conclusion(s) Intrauterine application of ACP gel after D&C for miscarriage in women with at least one previous D&C seems to reduce the incidence and severity of IUAs but does not eliminate the process of adhesion formation completely. Future studies are needed to confirm our findings and to evaluate the effect of ACP gel on fertility and reproductive outcomes. Clinical Trial Registration Number NTR 3120.