Preterm delivery is one of the main causes of perinatal mortality and morbidity and it accounts for 60 to 80% of deaths of infants without congenital anomalies.1 Moreover, preterm neonates are at high risk of developing cerebral palsy, visual and hearing impairment and chronic lung disease, while 40 to 60% of them will need special educational support. The preterm delivery rate varies between 5 to 7% in Europe and 11 to 12% in the United States. Despite the advances in obstetric care and neonatology the rate of preterm delivery was not decreased but in fact increased.2 This is mainly attributed to the increased number of preterm births among multiple gestations, the trend towards iatrogenic premature delivery in conditions such as hypertension or intrauterine growth restriction as well as the more accurate estimation and registration of gestational age. Neonatal survival improves as gestational age progresses. It increases from approximately 50% at 25 weeks’ gestation to over 97% at 33 weeks’ gestation.2 It is therefore, logical as the major benefits from delaying delivery are seen in this period, that greater attention has been focused on early preterm labor, before 32 weeks. Extensive research has been made so far, in methods of predicting preterm delivery in both asymptomatic and symptomatic patients. The absence of reliable criteria for the selection of at risk patients, as well as the absence of effective interventions to prevent prematurity are responsible for the controversial results reported in different studies. During the last few years a clear relationship has been established between decreased cervical length and the risk of spontaneous preterm delivery. Many studies dealing with the ultrasonographic evaluation of the cervix during the course of pregnancy have suggested that cervical changes may detect or exclude the risk of preterm delivery. Unfortunately, the heterogeneity of most of them resulted in mixed performance of this procedure as a screening test. Ultrasound examination of the cervix has been applied mainly in five categories: 1. Women with symptoms of preterm labor 2. Asymptomatic women at high risk of preterm delivery 3. Asymptomatic women at low risk of preterm delivery 4. Women with multiple gestations 5. Pregnancies complicated by preterm premature rupture of membranes (PPROM).