Urogenital infections with Chlamydia trachomatis belong to the most prevalent sexually-transmitted bacterial diseases. In women, they can cause chronic salpingitis with subsequent tubal infertility and ectopic pregnancies. In men, C. trachomatis can cause urethritis, prostatitis and epididymitis. Urogenital infections can be symptomatic or asymptomatic. Symptomatic urogenital infections might impair male fertility. In vitro, C. trachomatis affects sperm motility and viability. However, there is no clear evidence that asymptomatic urogenital infections have an adverse effect on male fertility. Because C. trachomatis can be sexually transmitted and lead to female infertility, it is also of significance in male infertility work-up. Because of their high sensitivity, nucleic acid amplification tests should be used to examine first-void urine specimens. Both partners should be treated. The role of Ureaplasma urealyticum in reproductive medicine has been discussed controversially. There is no evidence that U. urealyticum has a significant impact on female or male infertility.