Our objective was to assess the value of insulin-like growth factor binding protein-1 (IGFBP-1) and other tests for the diagnosis of rupture of the membranes (ROM). We included 49 women with suspected ROM. The gold standard for membranes status was defined based on clinical examination, ultrasonography, tests results (except IGFBP-1) and labour information. Sensitivity, specificity, positive predictive value and negative predictive value of each test were as follows, respectively: IGFBP-1 (86, 74, 73 and 87%); bromothymol (64, 100, 100 and 77%); fern test (62, 96, 93 and 75%) and ultrasonography (19, 100, 100 and 61%). The detection of IGFBP-1 in vaginal secretions has high sensitivity for the diagnosis of ROM.