Premature rupture of membranes (PROM) is sometimes difficult to diagnose. This report proposes the use of alpha-feto-protein (AFP) values in vaginal secretions for diagnostic tests. Our investigation took place in two separate phases. The first phase validated the AFP test using an immuno-enzymatic assay method and determined a threshold value from a sample of 167 female patients (Group 1: 133 patients with an extremely low probability of PROM, and Croup 2: 54 patients with confirmed PROM). In the second phase the test was applied to a sample of 145 female patients (Group 3) with suspected, but unconfirmed, PROM. Results from alpha-feto-protein (AFP) evaluation were compared with data obtained from clinical. echographic and other tests. The positive/negative threshold adopted was an AFP concentration of 30 μg/l. For the two first groups, 1 and 2, sensitivity and specificity was in the 98%) to 99% confidence level. For Group 3, sensitivity and specificity results at the 30 μg/1 threshold value were 94.5′% and 95.4%) respectively. Quantitative measurement of AFP determined by imniuno-enzymatic assay of vaginal secretions with a threshold of 30μgil is a reliable, simple and rapid diagnostic test. Results obtained are significantly better than the measurement of pH. the determination of prolactin, and more practical than diamino-oxidase (DAO) assoys.