Two standardized techniques for in vivo and in vitro clinical evaluation of sperm migration are described. The in vivo test consists of postcoital sperm recovery, from the cervical canal and from the uterine cavity, with counts of: total number of sperm; number of motile sperm; and number of sperm with direct forward motility. The in vitro test is a capillary tube method which permits accurate measurement of four parameters: penetration depth; penetration density; qualitative motility; and survival of penetrated spermatozoa. Normal values for both tests were ascertained by means of serial determinations in a selected group of 22 women. Results obtained in this group were compared with the results obtained in a group of 14 patients with infertility due to cervical factor. In the infertile group the in vivo tests showed an almost complete absence of intrauterine sperm. In the in vitro test the most conspicuous alterations in the infertile cases were observed in: penetration depth at 10 min; density at 5 cm distance; and survival at 48 hr. The importance of standardized methods for the measurement of sperm migration, as well as the significance of these tests in the appraisal of both the cervical factor and sperm migration are discussed.