The effects of volume inseminated (20, 100 or 200 ml.) and number of sperm (1×109, 5×109 or 10×109) in all combinations on the transport of sperm and fertilization were studied. Effects were determined by recovering sperm and eggs from oviducts of gilts 6 or 8 hr. after experimentally controlled ovulation and 12 or 16 hr. after insemination, respectively. Sperm recovered from the oviducts and on the eggs were counted and fertility rate of eggs was determined. Gilts inseminated with 100 ml. of semen 12 hr. before egg recovery had a significantly (P9 or 10×109 sperm had significantly (P9 sperm. The addition of carbacholine or oxytocin had no effect on transport of sperm when inseminated in 20 ml. of semen. Carbacholine, when inseminated in 100 ml. of semen, increased significantly (P<0.05) the number of sperm recovered from the oviducts, but oxytocin had no effect. Volume of semen apparently affects the proportion of gilts in which sperm reach the site of fertilization, while the number of sperm found in the oviduct is affected by the concentration of sperm inseminated. This suggests that some minimum volume of semen must be inseminated to achieve optimum fertility, and the concentration of sperm must also be maintained above some minimum value.