The aim of this guideline is to aid primary care physicians and gynaecologists in the initial evaluation of women with suspected endometrial hyperplasia, to recommend the use of the 2014 World Health Organization classification for endometrial hyperplasia by all health care providers, and to guide the optimal treatment of women diagnosed with endometrial hyperplasia.Physicians, including gynaecologists, obstetricians, family physicians, general surgeons, emergency medicine specialists; nurses, including registered nurses and nurse practitioners; medical trainees, including medical students, residents, and fellows; and all other health care providers.Adult women (18 years and older) presenting with suspected or confirmed endometrial hyperplasia.The discussion relates to the medical therapy as well as surgical treatment options for women with and without atypical endometrial hyperplasia.For this guideline, relevant studies were searched in PubMed, Cochrane Wiley, and the Cochrane Systematic Reviews using the following terms, either alone or in combination, with the search limited to English language materials, human subjects, and published since 2000: (endometrial hyperplasia, endometrial intraepithelial neoplasia, endometrial sampling, endometrial curettage, diagnosis) AND (treatment, progestin therapy, surgery, LNG-IUS, aromatase inhibitors, metformin ), AND (obesity). The search was performed in April 2018. Relevant evidence was selected for inclusion in the following order: meta-analyses, systematic reviews, guidelines, randomized controlled trials, prospective cohort studies, observational studies, non-systematic reviews, case series, and reports. Additional significant articles were identified through cross-referencing the identified reviews. The total number of studies identified was 2152, and 82 studies were included in this review.The content and recommendations were drafted and agreed upon by the authors. The Executive and Board of the Society of Gynecologic Oncology of Canada reviewed the content and submitted comments for consideration, and the Board of the Society of Obstetricians and Gynaecologists of Canada approved the final draft for publication. The quality of evidence was rated using the criteria described in the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology framework. The interpretation of strong and weak recommendations was also included. The Summary of Findings is available upon request.It is expected that this guideline will benefit women with endometrial hyperplasia. This should guide patient informed consent before both medical and surgical management of this condition.Evidence will be reviewed 5 years after publication to decide whether all or part of the guideline should be updated. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations.RECOMMENDATIONS.