Chlamydia trachomatis usually causes asymptomatic cervicitis, but it sometimes ascends into the uterine cavity, fallopian tubes, or peritoneal cavity, causing pelvic inflammatory disease and infertility. In this study, we examined endocervical chlamydial antigens and serum chlamydial antibodies in infertile women and laparoscopically evaluated pelvic lesions according to our pelvic scoring system. In patients testing positive for a chlamydial infection, the total pelvic score was significantly higher than in patients testing negative. When each area examined was assessed separately, however, only the tubal score was significantly higher in the chlamydia infected patients. These findings may indicate that tubal lesions are the major cause of infertility in women with chlamydial infections.