This was a retrospective study, carried out at Yeovil District Hospital, UK, from January 2006 to December 2008, looking at 40 patients with twin pregnancies. The aim was to evaluate the role of phosphorylated insulin-like growth factor binding protein-1 (IGFBP-1) test in the prediction of pre-term delivery in twin pregnancies. All the patients had a transvaginal ultrasound scan for cervical length at 24 weeks, followed by a high vaginal swab for IGFBP-1 at 26 weeks. A total of 95% of women screened negative for the IGFBP-1 test. None of these women delivered before 30 weeks; 7.50% delivered between 30 and 33+6 weeks; 87.5% delivered after 34 weeks. Two women (5.00%) screened positive for phosphorylated insulin-like growth factor binding protein-1; one had a spontaneous pre-term delivery at 30 weeks, while the other patient delivered at 38 weeks. It was concluded that women with twin pregnancies that have negative phosphorylated insulin-like growth factor binding protein-1 have a low risk of delivery before 34 weeks in the absence of other obstetric complications.