A total of forty male mice (32∼33 g average initial body weight) were used in a 10-d growth study to evaluate the effects of dietary yeast hydrolysate SCP-20 on reproductive function in male mice. Dietary treatments included 1) CON (basal diet) and 2) TRT (CON diet +1.5% yeast hydrolysate SCP-20). Testis weight of male mice fed TRT diets was higher than that of male mice fed CON diet (p<0.05). Also VSL was significantly (p<0.05) increased in male mice fed TRT diet compared to that in male mice fed CON diet. Male mice fed TRT diet showed significant (p<0.05) improvement in VAP (average-path velocity) and LIN (linearity) compared to male mice fed CON diet. Also, velocity of epididymal sperm of male mice fed TRT diets was higher than that of male mice fed CON diet (P<0.05). In conclusion, the results obtained from this trial suggests that the dietary yeast hydrolysate SCP-20 was an effective means of improving sperm velocity in male mice.