Background: Observational studies suggest higher pregnancy rates after the hysteroscopic removal of endometrial polyps, submucous fibroids, uterine septum or intrauterine adhesions, which are detectable in 10% to 15% of women seeking treatment for subfertility. Objectives: To assess the effects of the hysteroscopic removal of endometrial polyps, submucous fibroids, uterine septum or intrauterine adhesions suspected on ultrasound, hysterosalpingography, diagnostic hysteroscopy or any combination of these methods in women with otherwise unexplained subfertility or prior to intrauterine insemination (IUI), in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). Search methods: We searched the Cochrane Menstrual Disorders and Subfertility Specialised Register (6 August 2012), the Cochrane Central Register of Controlled Trials (T he Cochrane Library 2012, Issue 7), MEDLINE (1950 to October 2012), EMBASE (1974 to October 2012), CINAHL (from inception to October 2012) and other electronic sources of trials including trial registers, sources of unpublished literature and reference lists. We handsearched the American Society for Reproductive Medicine (ASRM) conference abstracts and proceedings (from January 2008 to October 2012) and we contacted experts in the field. Selection criteria: Randomised comparisons between operative hysteroscopy versus control in women with otherwise unexplained subfertility or undergoing IUI, IVF or ICSI and suspected major uterine cavity abnormalities diagnosed by ultrasonography, saline infusion/gel instillation sonography, hysterosalpingography, diagnostic hysteroscopy or any combination of these methods. Primary outcomes were live birth and hysteroscopy complications. Secondary outcomes were pregnancy and miscarriage. Data collection and analysis: Two authors independently assessed studies for inclusion and risk of bias, and extracted data. We contacted study authors for additional information. Main results: Two studies met the inclusion criteria and neither reported the primary outcomes of live birth and complications from the procedure. In women with otherwise unexplained subfertility and submucous fibroids, there is no evidence of benefit with hysteroscopic myomectomy compared to regular fertility-oriented intercourse during 12 months for clinical pregnancy (odds ratio (OR) 2.4, 95% confidence interval (CI) 0.97 to 6.2, P = 0.06, 94 women) and miscarriage (OR 1.5, 95% CI 0.47 to 5.0, P = 0.47, 94 women) (very low-quality evidence). The hysteroscopic removal of polyps prior to IUI increases the odds of clinical pregnancy (experimental event rate (EER) 63%) compared to diagnostic hysteroscopy and polyp biopsy only (control event rate (CER) 28%) (OR 4.4, 95% CI 2.5 to 8.0, P < 0.00001, 204 women, high-quality evidence). Authors' conclusions: Hysteroscopic myomectomy might increase the odds of clinical pregnancy in women with unexplained subfertility and submucous fibroids, but the evidence is at present not conclusive. The hysteroscopic removal of endometrial polyps suspected on ultrasound in women prior to IUI might increase the clinical pregnancy rate. More randomised studies are needed to substantiate the effectiveness of the hysteroscopic removal of suspected endometrial polyps, submucous fibroids, uterine septum or intrauterine adhesions in women with unexplained subfertility or prior to IUI, IVF or ICSI.