Objective: To find out if the shortened exposure of oocytes to sperm can influence the embryo quality and the implantation and pregnancy rate of the classical IVF also in Centre for Assisted Reproduction. Design: A prospective study including 104 patients undergoing the classical IVF procedure. Setting: Centre for Assisted Reproduction, Clinic of Gynaecology and Obstetrics, Palacký University Medical School and the University Hospital in Olomouc. Methods: In the study group with the shortened exposure (54 patients) the oocytes were washed one hour after the insemination and transferred into the fresh medium. In the control group (50 patients) the classical procedure (e.g. transfer into the fresh medium 17 to 20 hours after insemination) has been used. The following parameters have been evaluated in both groups: the stimulation protocol, sterility cause, number of previous IVF cycles, age, serum estradiol level on the day of hCG application, number of retrived oocytes, fertility rate (FR), embryo quality, pregnancy rate (PR) and the implantation rate (IR) expressed as the number of gestational sacs with heart action related to the number of transferred embryos. T-Test, Mann-Whitney Test and c2 were used for statistical evaluation. Results: There were no statistically significant differences between the study and the control group in any of the parameters compared. Conclusion: In our study group the shortened exposure of oocytes to sperm did not influence the results of the classical IVF.

        Key words: classical IVF (IVF + ET), shortened exposure of oocytes, embryo quality