Background: Observational evidence suggests a potential benefit with several anti-adhesion therapies in women undergoing operative hysteroscopy (e.g. insertion of an intrauterine device or balloon, hormonal treatment, barrier gels or human amniotic membrane grafting) for decreasing intrauterine adhesions (IUAs). Objectives: To assess the effectiveness of anti-adhesion therapies versus placebo, no treatment or any other anti-adhesion therapy, following operative hysteroscopy for treatment of female subfertility. Search methods: We searched the following databases from inception to June 2017: the Cochrane Gynaecology and Fertility Group Specialised Register; the Cochrane Central Register of Studies (CRSO); MEDLINE; Embase; CINAHL and other electronic sources of trials, including trial registers, sources of unpublished literature and reference lists. We handsearched the Journal of Minimally Invasive Gynecology, and we contacted experts in the field. We also searched reference lists of appropriate papers. Selection criteria: Randomised controlled trials (RCTs) of anti-adhesion therapies versus placebo, no treatment or any other anti-adhesion therapy following operative hysteroscopy in subfertile women. The primary outcome was live birth. Secondary outcomes were clinical pregnancy, miscarriage and IUAs present at second-look hysteroscopy, along with mean adhesion scores and severity of IUAs. Data collection and analysis: Two review authors independently selected studies, assessed risk of bias, extracted data and evaluated quality of evidence using the GRADE method. Main results: The overall quality of the evidence was low to very low. The main limitations were serious risk of bias related to blinding of participants and personnel, indirectness and imprecision. We identified 16 RCTs comparing a device versus no treatment (two studies; 90 women), hormonal treatment versus no treatment or placebo (two studies; 136 women), device combined with hormonal treatment versus no treatment (one study; 20 women), barrier gel versus no treatment (five studies; 464 women), device with graft versus device without graft (three studies; 190 women), one type of device versus another device (one study; 201 women), gel combined with hormonal treatment and antibiotics versus hormonal treatment with antibiotics (one study; 52 women) and device combined with gel versus device (one study; 120 women). The total number of participants was 1273, but data on 1133 women were available for analysis. Only two of 16 studies included 100% infertile women; in all other studies, the proportion was variable or unknown. No study reported live birth, but some (five studies) reported outcomes that were used as surrogate outcomes for live birth (term delivery or ongoing pregnancy). Anti-adhesion therapy versus placebo or no treatment following operative hysteroscopy. There was insufficient evidence to determine whether there was a difference between the use of a device or hormonal treatment compared to no treatment or placebo with respect to term delivery or ongoing pregnancy rates (odds ratio (OR) 0.94, 95% confidence interval (CI) 0.42 to 2.12; 107 women; 2 studies; I2 = 0%; very-low-quality evidence). There were fewer IUAs at second-look hysteroscopy using a device with or without hormonal treatment or hormonal treatment or barrier gels compared with no treatment or placebo (OR 0.35, 95% CI 0.21 to 0.60; 560 women; 8 studies; I2 = 0%; low-quality evidence). The number needed to treat for an additional beneficial outcome (NNTB) was 9 (95% CI 5 to 17). Comparisons of different anti-adhesion therapies following operative hysteroscopy It was unclear whether there was a difference between the use of a device combined with graft versus device only for the outcome of ongoing pregnancy (OR 1.48, 95% CI 0.57 to 3.83; 180 women; 3 studies; I2 = 0%; low-quality evidence). There were fewer IUAs at second-look hysteroscopy using a device with or without graft/gel or gel combined with hormonal treatment and antibiotics compared with using a device only or hormonal treatment combined with antibiotics, but the findings of this meta-analysis were affected by evidence quality (OR 0.55, 95% CI 0.36 to 0.83; 451 women; 5 studies; I2 = 0%; low-quality evidence). Authors' conclusions: Implications for clinical practice The quality of the evidence ranged from very low to low. The effectiveness of anti-adhesion treatment for improving key reproductive outcomes or for decreasing IUAs following operative hysteroscopy in subfertile women remains uncertain. Implications for research More research is needed to assess the comparative safety and (cost-)effectiveness of different anti-adhesion treatments compared to no treatment or other interventions for improving key reproductive outcomes in subfertile women.