Problem-Chlamydia trachomatis cause sexually transmitted infection and reproductive dysfunction worldwide. Identifying a population of endocervical T cells to target in vaccine development is likely to enhance efficacy of a vaccine and reduce reproductive tract dysfunction.Method of Study-Endocervical samples were obtained from young women and flow cytometric analysis was used to identify lymphocytes that appeared in the genital tract in response to bacterial sexually transmitted infections caused by C. trachomatis.Results-Increased numbers of α4β7+CLA+ memory T cells, a unique T cell phenotype, were found in the endocervix of human females infected with C. trachomatis.Conclusion-A unique population of memory T lymphocytes expressing both α4β7 and CLA gain access to reproductive tract tissues during a sexually transmitted infection with C. trachomatis and should be considered in development of vaccines against sexually transmitted infections.