Chlamydia trachomatis is an important pathogen in the aetiology of pelvic inflammatory disease, resulting in female infertility. If all female infertility patients are screened for silent genital chlamydia infection, should the male partners of these patients also be screened to decrease the risk of re-infection? To determine the incidence of current and present male infection with C. trachomatis, we carried out a prospective clinical study. We studied 100 consecutive new male partners of patients seen in the infertility clinic. The infertility was of at least 12 months duration. We used polymerase chain reaction detection of C. trachomatis in urine specimens and microimmunofluorescence serology was performed to detect both past and current infection. The female partners were also screened for chlamydia infection by cervical swabs and serology. In five male patients (5%) C. trachomatis DNA was detected in the urine specimen by polymerase chain reaction. Microimmunofluorescence serology was positive in five patients (5%). One of the subjects had positive serology and urine polymerase chain reaction testing. The proportion of male partners with current or previous C. trachomatis infection was therefore 9% (95% CI 3.39 - 14.60). Seven female patients had positive serology results (7%), one of whom also had a positive cervical swab result indicating current infection with the pathogen. In four cases, both the male and female partner had positive serology results. The cost of screening for C. trachomatis is cheaper than treating the complications of undiagnosed genital Chlamydia infection, which is implicated in tubal disease leading to infertility. The results suggest that routine screening of male partners in an infertility setting may be justified.