The Authors have considered the possibility of avoiding the ovarian hyperstimulation syndrome, (O.H.S.), in women undergoing treatment with ovulation inductors, (Clomiphene citrate and gonadotropin) by means of repetitive ultrasonographic scansion beginning from the eleventh day of the cycle. They have come to the conclusion that there should be a routine use of ultrasound in order to avoid the moderate and severe forms of this syndrome.