Infertile couples frequently experience sexual dysfunction during their infertility investigations, including inadequate vaginal lubrication. In a attempt to look for a lubricant that would not impair sperm motility and activity, saliva was added to normal semen from healthy male donors. Saliva induced a "shaking movement" in 12% of the total sperm population incubated with high concentrations of saliva. This phenomenon did not occur with low concentrations of saliva, but sperm motility and progression significantly decreased. The results indicate that saliva has a deleterious effect on sperm motility and activity and should not be encouraged as a vaginal lubricant for the infertile couple.