The effect of Laser light on the motility and the velocity of human spermatozoa were measured by means of multiple exposure photography. Total sperm motility increased after Laser irradiation at 4 J/cm2, 8 J/cm2 and 32 J/cm2 respectively with respect to control. However, no influence on sperm velocity was demonstrated after Laser irradiation. This observation suggests that Laser light stimulates non-motile live spermatozoa.