The implantation rates and subsequent pregnancy rates in in vitro fertilization (IVF) programs are lower than those currently seen in the normal fertile population. During IVF treatment regimens, intercourse is not allowed and artificial insemination is normally excluded. This trial, involving the deposition of semen in the high vaginal area, was undertaken for evaluation of the influence of sperm in the reproductive tract on subsequent implantation rates. The results show that the implantation rate, as assessed by a rise in the human chorionic gonadotropin levels in inseminated patients, was 53%, compared with 23% in the control group. The implantation rate of 54% in the group who had tubal occlusion or no fallopian tubes was not significantly different from the implantation rate of 50% in the group with patent tubes, which suggests that the site of sperm influence was on the endometrium and that the absence of the fallopian tube has no significant effect upon this influence.