['Estrogen and estrogen receptors are known to play important roles in the pathophysiology of pelvic organ prolapse (POP). We investigated whether estrogen receptor beta (ERbeta) gene polymorphisms were associated with POP by conducting a case-control association study in 69 women with POP and 141 women without POP.', 'Genotypes of the ERbeta gene polymorphisms (rs2987983, rs1271572, rs944459, rs1256049, and rs1255998) were determined by polymerase chain reaction, followed by restriction fragment length polymorphism analysis. Haplotyping analysis was used to determine the relationship among five polymorphisms in the ERbeta gene and POP.', 'There was no significant difference between women with and those without POP in the distribution of any of the genotypes evaluated. In haplotype frequency estimation analysis, haplotype CGCGC was more prevalent in women with POP (16.7%) than in women without POP (8.9%) (p=0.011). Using multivariable logistic regression, age, parity and haplotype CGCGC were significantly associated with POP.'] Is estrogen receptor beta gene haplotype associated with pelvic organ prolapse?