Objective    To investigate the semen relative parameters and their effects on fertilization outcomes.     Methods    Totally 408 semen samples with normal fertilization rates in conventional in vitro fertilization and embryo transfer (IVF-ET) cycles in our department from January 2006 to July 2008 were collected. The relationship of the semen parameters and fertilized outcomes were retrospectively analyzed.     Results    Among 408 samples

there were 399 samples (about 97.79%) had normal sperm density

but only 21 samples (5.15%) had normal mot

ility. The sperm density was 3 to 400 10

6

/ml

its motility 10% to 85%

percentage of progres sive motile sperm (PMS%) 2% to 40%

and total progressive motile sperm count (TPMSC) was 2 to 597×10

6

. The motility

PMS% and total sperm count after sperm separation were positively correlated with the density

motility

PMS% and TPMSC before separation (P0.05). There was a positive correlation between the fertilization rate and separated sperm motility (r=0.132

P0.01)

other parameters have no effect on fertilization rate.     Conclusion    Semen parameters have a wild range for the patients with normal fertilization rate in conventional IVF. Mild and moderate oligoasthenospermia maybe have no effect on  fertility. However

the motility after sperm separation can affect fertilization rate.