Our purpose was to determine whether funnelling of the cervical internal os, length of the endocervical canal, cervical index, funnel length and funnel width determined by transvaginal sonography are predictive of recurrent preterm labour. Of 112 women, 65 admitted to the hospital for preterm labour with intact membranes had transvaginal sonographic evaluation of the cervix before digital cervical examination and institution of tocolysis. The following measurements were obtained: (1) presence of funnelling, (2) endocervical canal length, (3) cervical index, (4) funnel length and (5) funnel width. Logistic regression analysis was performed to determine the variables that made a significant contribution to the prediction of recurrent preterm labour. A total of 65 eligible women completed the study. Recurrent preterm labour was significantly associated with the presence of funnelling (85.2% vs. 23.3%) and short endocervical canal length, large cervical index and long funnel length as noted on transvaginal cervical sonography. The presence of funnelling, shorter endocervical canal length, larger cervical index and longer funnel length were suggestive of true preterm labour and its recurrence. Transvaginal sonographic examination of the uterine cervix is a useful procedure to predict recurrent preterm labour with intact membranes. (C) 1997 Elsevier Science Ireland Ltd.