Objective: To evaluate the association between the presence of uterine leiomyomas and three functional single nucleotide polymorphisms (SNPs) of the estrogen receptor alpha (ESR1), catechol- O- methyltransferase (COMT), and cytochrom P450 17 (CYP17A) genes, which have been described to modify the estrogen metabolism. Design: Prospective case control study. Setting: Academic research institution. Patient(s): One hundred thirty women with clinically and surgically diagnosed uterine leiomyomas and 139 population controls. Intervention(s): Peripheral venous puncture. Main Outcome Measure(s): Polymerase chain reaction and pyrosequencing were performed to genotype women with respect to the ESR1 IVS1- 397 T/C (PvuII), COMT G158A, and the CYP17A 34T→ C SNPs. Result(s): Comparing women with uterine leiomyomas and controls, no statistically significant differences with respect to allele frequency and genotype distribution were ascertained for ESR1 IVS 1- 397 T/C (PvuII) (P=0.9 and P=0.6, respectively), COMT G158A (P=0.3 and P=0.6, respectively), and CYP17A 34T→ C (P=0.1 and P=0.5, respectively). When all two- way interactions of investigated SNPs were ascertained, no significant interactions were observed. In a multivariate model, no SNP was significantly associated with leiomyomas. Conclusion(s): Carriage of the ESR1 IVS1- 397 T/C (PvuII), COMT G158A, and the CYP17A 34T→ C SNPs is not associated with the susceptibility to uterine leiomyoma in a Caucasian population. Objective: To evaluate the association between the presence of uterine leiomyomas and three functional single nucleotide polymorphisms (SNPs) of the estrogen receptor alpha (ESR1), catechol-O-methyltransferase (COMT), and cytochrom P450 17 (CYP17A) One of three women with clinically and surgically diagnosed uterine leiomyomas and 139 population controls. Intervention (s): Peripheral venous puncture Main Outcome Measure (s): Polymerase chain reaction and pyrosequencing were performed to genotype women with respect to the ESR1 IVS1-397 T / C (PvuII), COMT G158A, and the CYP17A 34T → C SNPs. women with uterine leiomyomas and controls, no significant significant differences with respect to allele frequency and genotype distribution were ascertained for ESR1 IVS 1-397 T / C (PvuII) (P = 0.9 and P = 0.6, respe When all two-way interactions of investigated SNPs were ascertained, no significant interactions were found (P = 0.3 and P = 0.6, respectively), and CYP17A 34T → C Conclusion (s): Carriage of the ESR1 IVS1-397 T / C (PvuII), COMT G158A, and the CYP17A 34T → C SNPs is not associated with the susceptibility to uterine leiomyoma in a Caucasian population.