Aim: To study the relationship between Ureaplasma urealyticum (UU) infection and apoptosis of human spermato-genic cells. Methods: Spermatogenic cells were observed under light microscope with Wright-Giemsa staining andby means of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end labeling(TUNEL) technique. Results: Apoptotic rate of UU-infected males (15.5 % ± 6.8 % ) was significantly higherthan that of controls (5.2 % ± 2.3 % ). Conclusion: Apoptosis of spermatogenic cells can be caused by UU in-fection, which provides further evidence for UU-induced male infertility. (Asian J Androl 1999 Sep ; 1: 127 - 129) Aim: To study the relationship between Ureaplasma urealyticum (UU) infection and apoptosis of human spermato-genic cells. Methods: Spermatogenic cells were observed under light microscope with Wright-Giemsa staining and by means of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) - Results: Apoptotic rate of UU-infected males (15.5% ± 6.8%) was significantly higherthan that of controls (5.2% ± 2.3%). Conclusion: Apoptosis of spermatogenic cells can be caused by UU in-fection, which provides further evidence for UU-induced male infertility. (Asian J Androl 1999 Sep; 1: 127-129)