Abstract: Objective To explore the association between body mass index(BMI),waist to hip ratio(WHR)and clinical benign prostatic hyperplasia(BPH)risk in older men.Methods A hospital-based case-control study was conducted.Cases(n=280)were men surgically and histologically confirmed with BPH,and controls(n=280)were men admitted to hospital for different diseases not related with prostatic conditions.Using a structured questionnaire,all subjects were interviewed and waist and hip circumference of the subjects were measured.The odds ratios(OR)and 95% confidence intervals(CI)of BPH for BM I and WHR were estimated with unconditional multiple logistic regression models.Results WHR≥0.9 was positively related to BPH(compared with WHR<0.9:O R=1.16,95% CI 1.05～4.87,P<0.05).Age-adjusted relative risks for BPH in WHR≥0.9 versus WHR<0.9 stratified by BM I(obesity)were estimated.For men who were overweight(BM I 24.0～27.9)or obesity(BM I≥28.0),WHR≥0.9 was associated with a significantly increased risk for clinical BPH(compared with WHR<0.9:OR=2.65,95% CI 1.33～6.96 and O R=3.00,95% CI=1.81～8.84,respectively).Conclusion Obesity(especially central obesity)is an important risk factor of clinical BPH.For overweight or obesity,central obesity is associated with a significantly increased risk of clinical BPH.