Vaginal pessaries have been reported to be useful in women who are at risk of preterm delivery since 1959. Bedrest and cervical cerclage have become standard therapy for women with cervical insufficiency. However, cerclage is not without risk. Furthermore, advances in ultrasound have allowed us to identify women who are potentially at risk of preterm delivery by detecting cervical shortening before dilatation. A variety of studies suggest that pessaries can increase the percentage of full-term deliveries when used in women with an incompetent cervix. Pessary use should be considered as adjuncts to cerclage or as a solution for women who are not good candidates for cerclage. This article reviews the published literature concerning the use of pessaries in women with an incompetent cervix or at risk of early delivery.