Abstract: Objective To examine the association between the intakes of dietary protein,milk and dairy products and the risk of benign prostatic hyperplasia(BPH).Methods A case-control study was conducted among 360 men who were aged 50-90 years and surgically treated for BPH betw een 2007 and 2009 and 360 gender and age-matched controls who were admitted to the same hospital for diseases other than prostatic conditions.The cases and controls were interviewed during their hospitalization with a standardized structured questionnaire.Data on diet were obtained via a valid semi-quantitative food frequency questionnaire(FFQ).Odds ratios(OR) and corresponding 95% confidence intervals(CI) of the variables were estimated using unconditional multiple logistic regression model.Results The proportion of the cases living in the rural area was significantly higher than that of in the controls (28.3% vs 16.7%,P< 0.05).After adjusting for age and energy intake,the total protein intake was inversely related to BPH (χ²=8.567,P=0.036).Men in the highest quartile of total protein intake were nearly a half less likely to report BPH(OR=0.615,95% CI=0.014-0.930).The consumptions of animal protein and milk and dairy products were inversely related with BPH(χ²=10.572,P=0.014 and OR=0.731,95% CI:0.545-0.981,respectively).The relation was attenuated among the subjects with high intake of animal protein (OR=0.638,95%CI:0.418-0.972 and OR=0.636,95%CI:0.292-0.835,respectively).Conclusion Dietary protein,especially animal protein,was inversely related to BPH.But the relation was attenuated by high intake of animal protein.