Introduction: Ureaplasma urealyticum genital infection is a sexually transmitted that is involved in non-gonococcal urethritis, prostatitis, epididymitis, and infertility. The organism is seen in infertile couples more commonly than in healthy couples. U. urealyticum infection not only jeopardizes fertility but also poses infertility treatment and the resultant pregnancies at risk. Diagnosis of U. urealyticum infections by conventional bacterial methods is very difficult. The aim of this study was to compare culture with Polymerase Chain Reaction (PCR) for detection of U. urealyticum in semen of infertile and healthy men.

 Methods: From each of the two groups of infertile and healthy men who referred to infertility treatment center of Rouyan Institute in Tehran, 100 semen specimens were obtained. Regular spermogram was done. Bacterial DNA was extracted with Cadieux method and analyzed with PCR protocol, using species-specific primers for U. urealyticum (urease gene). Bacterial culture was done with broth-agar method.

 Results: U. urealyticum was detected by PCR in 12 semen specimens (12%) from infertile patients and in three specimens (3%) from healthy men. Result of culture was positive in five specimens (5%) from infertile patients and in one specimen (1%) from healthy men. The volume of seminal fluid, number of sperm cells, and percent of sperm cells with normal morphology were significantly decreased in infertile men. These three parameters were lower in infertile men with PCR positive than in infertile men men with PCR negative results.

 Conclusion: Since U. urealyticum has a potential causative role in several sexually transmitted diseases, reproductive failure, and neonatal morbidity and mortality, its detection with PCR is important and necessary in infertile couples. PCR is a sensitive method, and it is more rapid than culture for the detection of U. urealyticum in the clinical specimens (<24 hour hours versus 2-4 days).

 Hakim Research Journal 2007 10(3): 48 - 53.