The ejaculate used for in-vitro fertilization of human oocytes must fulfil minimum requirements. Based on the results of experimental investigations, total concentrations of spermatozoa must be greater than 5 million spermatozoa/microliters with progressive motilities of at least 30% and also a normal morphology of at least 30%. Furthermore, in sperm preparations used for inseminating human oocytes, the concentration of pathogenic microorganisms must not be less than 10(4). If there are positive bacteriological findings, the treatment of both partners is mandatory according to the antibiogram. According to the information gathered to date, the hamster oocyte penetration test can only provide additional information if it is positive, but acceptance into an IVF programme should not depend on this test. According to the results presented so far, the swell test developed by Jeyendran shows quite good correlation with the fertilization of human oocytes.