Seventy-five patients with a total of 306 human menopausal gonadotropin treatment cycles over the period 1984-1989 were analysed retrospectively to evaluate the value of transabdominal pelvic ultrasonography in prevention of complications arising from ovulation induction with human menopausal gonadotropins. There were 60 pregnancies giving a pregnancy rate of 19.6% per cycle. There was positive correlation between the number of follicles > or = 14 mm in mean diameter and the incidence and degree of hyperstimulation (p < 0.005) as well as the incidence of multiple pregnancies (p < 0.01). Ultrasonography is a useful adjunct for monitoring in such a program.