Preterm premature rupture of membranes (PPROM) is closely related with maternal and fetal complications. Therefore, early diagnosis is extremely important to provide maternal and fetal well-being. Many inflammatory markers have been evaluated for their ability to diagnose membrane rupture at early stages. The aim of this paper is to investigate peripheral blood platelets, neutrophils and lymphocytes counts in women with preterm premature rupture of membranes (PPROM) and threatened preterm labour (TPL) compared with gestation-matched controls in order tolearn how they change. This is case – control study, was conducted at Obstetrics and Gynecology department in Al-Zahraa university hospital, Cairo, Egypt, on 80 pregnant women was divided into 3 groups; (group1); included 30 controls, (group 2a); included 25 preterm premature rupture of membranes, (group 2b); included 25 threatened preterm labor. There was statistically significant difference between the three studied groups regarding NLR. There was no statistically significant difference between the three studied groups regarding platelets and PLR. Based on our finding, NLR in preterm premature rupture of membranes group was significantly higher than in those had threatened preterm labor and control group. The leukocytes, neutrophils, lymphocytes, NLR and CRP statistically significant predictors of the preterm premature rupture of membranes, to be able to extrapolate these findings into clinical daily practice, further studies are needed.