This study analyzed the association of the alleles, genotypes, and haplotypes of the CTLA4 SNVs rs5742909 (−318 C>T), rs231775 (+49 A>G), and rs3087243 (+6230 G>A) with HPV infection, the development of low-grade squamous intraepithelial lesions (LSILs), high-grade squamous intraepithelial lesions (HSILs), and cervical cancer in 445 women treated by the public health service of Paraná, Brazil. Here, CTLA4 is linked to squamous cell intraepithelial neoplasia.