Background Uterine fibroids (UFs) are the most common neoplasm affecting women that can cause significant morbidity and may adversely impact fertility.Objectives To examine UF epidemiology and to evaluate the relative strengths of putative risk factors.Search strategy MEDLINE and Embase were searched for studies published in English between January 1995 and April 2015.Selection criteria Publications reporting relevant data from registries and other observational studies with over 1000 patients and single-centre studies with over 100 patients were selected.Data collection and analysis Data on UF incidence, prevalence and associated risk factors were extracted from 60 publications.Main results Wide ranges were reported in both UF incidence (217-3745 cases per 100 000 women-years) and prevalence (4.5-68.6%), depending on study populations and diagnostic methods. Black race was the only factor that was recurrently reported to increase UF risk, by two-threefold compared with white race. Eleven other factors affected UF risk to a magnitude similar to or greater than race. Age, premenopausal state, hypertension, family history, time since last birth, and food additive and soybean milk consumption increased UF risk; use of oral contraceptives or the injectable contraceptive depot medroxyprogesterone acetate, smoking in women with low body mass index and parity reduced UF risk.Conclusions We identified 12 risk factors that play an important role in UF epidemiology. The UF risk factor with the strongest evidence is black race. High-quality prospective observational data are needed to improve our understanding of UF epidemiology, and thus its aetiology and optimal management.Keywords Epidemiology, incidence, leiomyoma, prevalence, race, risk factors, uterine fibroids.Tweetable abstract Uterine fibroids occur in about 70% of women. Black race and 11 other factors affect uterine fibroid risk.