Purpose: To evaluate the possible role of apoptosis in the rupture of chorio-amniotic membranes obtained from the pregnancies with premature rupture of the membranes and to compare the results with control. Methods: Fetal membranes from 50 pregnancies were included in the study. 30 of 50 pregnancies had premature rupture of membranes. 20 pregnancies with intact membranes during labor served as controls. Chorio-amniotic membrane biopsies were taken from the rupture site of membrane and the periphery of the rupture site. in the control group, membrane biopsies were taken from the artificial rupture site or cervical pole of the membranes and the membranes close to the edge of the placenta. in recognizing apoptotic figures, routinely processed samples were stained with hematoxylin and eosin for light microscopic examination. Quantification of apoptotic cells was performed in high power fields containing approximately 5000 cells and expressed as the number per hundred cells. Results: Apoptotic cells were detected, in the amniotic epithelium, in chorionic plate including the trophoblastic layer and in the fibroblastic layer of the fetal membranes. the apoptotic cells were mostly found in the chorionic trophoblastic cells. There was statistically significant difference between the apoptotic index of the premature rupture of the membranes and the control group in both rupture and peripheral sites (p<0.05). the apoptotic index of the chorio-amniotic cells was insignificantly higher in the rupture sites of the membrane than in the peripheral site in pregnancies with premature rupture of the membranes (0.253%± 0.09, 0.142%± 0.04, respectively, p=0.139). There was also no significant difference between the artificially ruptured membrane site and the intact peripheral site in pregnancies without premature rupture of the membranes (0.124%± 0.08, 0.089%± 0.02, respectively, p=0.708). Conclusion: the results of this study demonstrate that apoptosis with the company of many other factors can be associated with premature rupture of membranes
