We analysed the risk factors for clinically diagnosed uterine fibroids in women attending menopause clinics in Italy. Between 1997 and 2003 we conducted a large cross-sectional study on the characteristics of women around menopause attending a network of first-level outpatient menopause clinics in Italy for general counselling about menopause or treatment of menopausal symptoms. A total of 85,967 non-hysterectomized women not reporting myomectomy entered the study; 2239 had a diagnosis of uterine fibroids. A woman was defined as having uterine fibroids if she had at gynecological examination an enlarged uterus (2 months of gestation or more) and a clinical diagnosis of fibroids. In 769 cases was performed in ultrasound examination which confirmed the diagnosis. In comparison with women with a body mass index (BMI) <22, the multivariate ORs for BMI 26 or more were 1.30 (95% CI, 1.09-1.55) for cases with clinical diagnosis, and 1.29 (95% CI, 1.01-1.45) for women with ultrasonographic diagnosis. In comparison with premenopausal women, the multivariate OR for clinically detected fibroids was 0.63 (95% CI, 0.55-0.72) for post-menopausal ones. The risk of fibroids was lower in parous women than in nulliparous ones, and the risk decreased with number of births regardless the type of diagnosis. This study confirms in a large sample that parity is the main protective factor for the development of fibroids. Overweight increases the risk.