The objective of this study was to verify the possible association between the Sp1-binding site polymorphism and genital prolapse. A case-control study was conducted in 107 patients with stages III and IV genital prolapse. The control group included 209 women with stages 0 and I. The polymorphism of type I collagen Sp1-binding site was identified by amplification of the first intron of the COL1A1 gene. We did not find differences in the prevalence of the GT and TT genotypes between the groups (p = 0.34), even when we grouped patients with at least one polymorphic allele (GT and TT) and compared them with patients without the polymorphic allele (GG; p = 0.17) The presence of at least one vaginal delivery, family history for prolapse, and macrosomatic fetus were independent risk factors for prolapse. In conclusion, the COL1A1 Sp1-binding site was not significantly associated with genital prolapse among our study subjects.