Objective: To determine whether preterm premature rupture of the membranes (PPROM) is caused by a generalised and/or localised reduction in the hydroxyproline content of the amniotic membrane. Material and Methods: This study included 105 parturient women who delivered between September 2005-March 2006 in Zekai Tahir Burak Women's Health Education and Research Hospital High Risk Pregnancy Department. The first group included 40 parturient women with PPROM. The second group included 65 parturient women with intact membranes having an elective Caesarean section with the diagnosis of previous caesarean section. In the PPROM group (n=40), 25 women delivered vaginally and 15 women had an emergency Caesarean section for fetal distress at the beginning of labour. The hydroxyproline content of the amniotic membranes of 40 women with preterm premature rupture of the membranes was compared with these of 65 women who delivered by elective Caesarean section. Three regions of the amniotic membrane were examined: 1) the rupture site 2) the midzone area, which was the halfway between the rupture site and placental edge; and 3) periplacental area, which was usually 10-12 cm away from the rupture site. Results: In the rupture site, no significant difference was detected in the hydroxyproline content between the control group (0.17-0.63 mg/mg protein) and the PPROM group (0.26-0.51mg/mg protein) (p=0.916). In the midzone area, there was no significant difference between the control group (0.16-1.45 mg/mg protein) and the PPROM group (0.24-0.84 mg/mg protein) (p=0.462). In the periplacental area there was no significant difference between the control group (0.23-1.35 mg/mg protein) and the PPROM group (0.23-1.13 mg/mg protein) (p=0.753). Conclusion: Preterm premature rupture of the membranes does not appear to be accompanied by a generalised or localised reduction in the collagen of amniotic membrane.