Objective: The penetration of native and cryopreserved human spermatozoa into cervical mucus – the Kremer’s test. Design: Retrospective study. Setting: Department of Obstetrics and Gynaecology, Medical Faculty, Charles University and Faculty Hospital, Plzeň. Methods: Human cervical mucus was collected from 73 women visiting the Division of immunolo- gy of reproduction, Department of Obstetrics and Gynaecology in Plzeň. Native spermatozoa was obtained from the patients of the Division of Immunology of Reproduction as well. Cryopreserved only in its seminal plasma was obtained from the spermabank of our department. The distance of penetration in centimetres from the start was examined in inverse microscopy after 30, 60, 90 and 90 minutes. Also the character and duration of the sperm motility was analyzed. Results: The penetration of native spermatozoa was higher than the penetration of cryopreserved spermatozoa in each case. The native spermatozoa had a higher penetrability, motility and life- ability. Spermatozoa preserved only in its seminal plasma had the parametres demonstrably lower. Nevertheless these spermatozoa can be successfully used for homologue or heterologue insemination or for IVF because these spermatozoa do not loose its enzymatic and remaining energetic equipment by penetration the cervical canal. Conclusion: The Kremer’s test belongs to the reliable methods of penetration ability of native and cryopreserved sperms.

        Key words: Kremer’s test, sperm, ovulatory mucus