Chlamydia trachomatis(CT)infection is the most prevalent sexually transmitted bacterial disease worldwide.However,unlike that in female infertility,the role of CT infection in male infertility remains controversial.The objective of this retrospective study was to explore the impacts of CT infection in the genital tract on sperm quality,sperm acrosin activity,antisperm antibody levels,and inflammation in a large cohort of infertile males in China.A total of 7154 semen samples were collected from infertile male subjects,416 of whom were CT positive(CT+group)and 6738 of whom were CT negative(CT-group),in our hospital between January 2016 and December 2018.Routine semen parameters(semen volume,pH,sperm concentration,viability,motility,morphology,etc.),granulocyte elastase levels,antisperm antibody levels,and sperm acrosin activity were compared between the CT+and CT-groups.Our results showed that CT infection was significantly correlated with an abnormally low semen volume,as well as an increased white blood cell count and granulocyte elastase level(all P＜0.05)in the semen of infertile males;other routine semen parameters were not negatively impacted.The antisperm antibody level and sperm acrosin activity were not affected by CT infection.These findings suggested that CT infection might contribute to inflammation and hypospermia but does not impair sperm viability,motility morphology,and acrosin activity or generate antisperm antibodies in the infertile males of China.