Purpose of Investigation: To review the evidence concerning the efficacy of levonorgestrel-releasing intrauterine system (LNG-IUS) in preventing endometrial pathology in women treated with tamoxifen. Materials and Methods: Randomized controlled trials (RCTs) of women with breast cancer on tamoxifen that compared endometrial surveillance or placebo alone vs. the LNG-IUS were reviewed. The eligible trials were identified from the following electronic databases: Cochrane CENTRAL, Medline, and EMBASE. The authors extracted data on all reported outcomes and conducted meta-analyses on the endometrial polyps, endometrial hyperplasia, proliferative endometrium, and endometrium thickness. Results: According to the subgroup analysis, a significant reduction of endometrial polyps was obtained (OR=0.22, 95% CI 0.13-0.37, p < 0.00001). The use of LNG-IUS reduced the incidence of endometrial hyperplasia (OR=0.13, 95% CI 0.03-0.58, p = 0.007) Increased abnormal vaginal bleeding for LNG-IUS users may be an adverse aspect of LNG-IUS. Conclusion: This meta-analysis confirms that endometrial hyperplasia is also reduced as well as endometrial polyp formation reduced after long-term follow-up.