Background: The purpose of the present study is to evaluate β-hCG in vaginal washing fluid for the diagnosis of preterm premature rupture of membranes (PROM). Methods: This clinical trial was carried out at El-Galaa Maternity Teaching Hospital. The study included 100 women who were in their 3^rd trimester of pregnancy. They were divided into 2 groups; group І (case group): Pregnant women with definite history of premature rupture of membranes confirmed by speculum examination as patients' (PROM) group. (n =50) and group ІІ (control group): Pregnant women with no history of rupture of membranes as control group. (n = 50) Results: There was significant statistical difference in the prediction of PROM between the case group and the control group. Conclusion: The presence of vaginal HCG is highly predictive of membranes rupture and is a more accurate diagnostic test than the amniotic fluid index (AFI) assessment in the diagnosis of ROM.