Abstract: ObjectiveA case-control study was conducted to explore the risk factors of hyperplasia of mammary gland in Changzhou city,Jiangsu province.Methods309 new cases diagnosed hy perplasia of mammary gland and 323 controls matched by age frequency in the body examination of gynaecology in the Health Care Center of Women and Children of Zhonglou district,Changzhou city were investigated by in-person interview during 1st,July and 30th,October,2005.Non-conditional Logistic regression model analysis was used to find the significant risk factors of hyperplasia of mammary gland.ResultsThe BMI more than 22.6 kg/m² 5 years ago,having taken anti-latic excreting medicine or injection,,family history of hyperplasia of mammary gland,X-ray exposure,premature were the risk factors of hyper plasia of mammary gland.Compared to the baseline group,the odd ratios(ORs)were 1.87(95% CI:1.15~3.03),2.18(95% CI:1.19~4.01), 3.77(95% CI:2.07~6.89),1.88(95% CI:1.16~3.05)and 2.26(95% CI:1.04~4.89)respectively;more number of living birth,intake more vegetable and green tea were the protective factors for the hyperplasia of mammary gland,the ORs were 0.13(95% CI:0.02~0.82),0.46(95% CI:0.26~0.81) and 0.33(95% CI:0.12~0.89).ConclusionBMI more than 22.6 kg/m² 5 years ago,having taken anti-latic excreting medicine or injection,family histo ry of hyperplasia of mammary gland,X-ray exposure and premature of herself were associated with increased risk of hyperplasia of mammary gland.More number of living birth,intake more fresh vegetables and green tea may decrease risk of hyperplasia of mammary gland.