In this study the presence of Mycoplasma species in patients suffering from infertility was examined. 41 women and 37 men were examined, including 31 couples, and ten single women and six single men. Samples of vaginal and cervical mucus were taken from each woman, and samples of seminal fluid from each man. Identification and typing of the organisms were performed on the basis of microscopic and cultural characteristics and inhibition of growth by specific antibodies. Out of the 78 patients examined, 35 harboured Mycoplasma, either as Ureaplasma urealyticum or Mycoplasma hominis. Further investigation is needed to determine the clinical significance of these findings.