To determine the value of transvaginal sonography in women with a previous history of second trimester miscarriage due to cer­vical incompetence, 55 patients were subjected to either elective cervical cerclage or follow-up (every second patient) with weekly evaluations of the cervix by transvaginal ultrasonography. Emergency cerclage was applied when significant cervical changes were noted. All patients were evaluated with cervical cultures and ultrasound. Women with infection, fibroids, uterine malformations and multiple pregnancies were excluded from the study. The study population was divided in two groups. In group Ⅰ (n = 27) elective cerclage was applied during the 14th week. Women in group II (n = 28) were subjected to serial weekly evaluations of the cervix by transvaginal ultrasonograms. In 18 cases emelgency cerclage was applied due to significant cervical changes. In group I, labor started before the 33rd week in two cases (7.4%), between 33 and 37 weeks in nine (33.3%) and after the 37th week in 16 cases (59.2%). Out of the 18 patients in group II who had cervical cerclage after ultrasonographic evaluation, four (22.2%) delivered before the 33rd week, three (16.6%) between 33 and 37 weeks and 11 (61.1 %) after the 37th week. No statistical difference was noted between the two groups referring to pregnancy outcome (p < 0.1). We concluded that ultrasound-guided management despite cervical shortening, does not result in unfavorable pregnancy outcome A significant number of patients can avoid the operation.