To review the available data in the literature on the use of pessaries in preventing preterm birth. We searched PubMed and the Cochrane library with pessary preterm birth. Fifty-eight papers were identified, most of them with little scientific value. A randomized study, including 385 singleton pregnancies with a transvaginal ultrasound cervical length less than 25 mm between 18 and 22 WG, shows a reduction of spontaneous prematurity before 34 WG in the pessary group, with an OR of 0.18 (95%CI: 0.08-0.37). Another study on multiple pregnancies randomized between 12 and 20 WG, with a cervix measured by ultrasound between 16 and 22 WG, showed a reduction of neonatal morbidity in the pessary group (RR: 0.42; 95%CI: 0.19-0.91) in a sub-group with a cervical length<38 mm. These first results from randomized controlled study are encouraging. Other studies on singleton and twin pregnancies are ongoing or about to start.