We evaluated the interactive effect of polymorphisms in the sex hormone-binding globulin (SHBG) gene with soy isoflavones, tea consumption, and dietary fiber on endometrial cancer risk in a population-based, case-control study of 1,199 endometrial cancer patients and 1,212 controls. Genotyping of polymorphisms was performed by using TaqMan (Applied Biosystems, Foster City, CA) assays (rs6259) or the Affymetrix MegAllele Targeted Genotyping System (Affymetrix, Inc., US) (rs13894, rs858521, and rs2955617). Dietary information was obtained using a validated food frequency questionnaire. A logistic regression model was employed to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs). We found that the Asp(327)Asn (rs6259) polymorphism was associated with decreased risk of endometrial cancer, particularly among postmenopausal women (OR = 0.79, 95% CI = 0.62-1.00). This single nucleotide polymorphism (SNP) modified associations of soy isoflavones and tea consumption but not fiber intake with endometrial cancer, with the inverse association of soy intake and tea consumption being more evident for those with the Asp/Asp genotype of the SHBG gene at Asp(327)Asn (rs6259), particularly premenopausal women (P(interaction) = 0.06 and 0.02, respectively, for soy isoflavones and tea intake). This study suggests that gene-diet interaction may play an important role in the etiology of endometrial cancer risk.