Objectives : To compare the placental infalammation between preterm and term deliveries. Methods : Placentas were obtained in 116 preterm and 134 term single live births at the Yonsei University Medical Center between January 1992 and December 1993. Pathlogic examination of placenta was done by two pathologists. Examnied placental sites were fetal membrane , placental disc, decidua, and umbilical cord. Student`s test and Fisher`s exacte test were used for statical comparisons. Results : 1) The prevalence of histologic chorioamnionitis in premature ruptrue of membrane (PROM) group tends to be higher in preterem(46.7%) deliveries(term 15.4% p=0.05). In intact membrane group, the result was satistically significant between preterm(15.12%) and term(5.82%) deliveries(p=0.02) 2) In 207 patients with intact membrane , associations between placental inflammation and preterm deliveries were statistically significant in chorioamnionitis and cord inflammation(preterm 5.8%, term 0%, p0.1) 3) In 43 patients with PROM no significant association was noted between placental inflammation and preterm deliveries. 4) Histologic choriamnionitis was more severe in preterm deliveries. 5) in 97 patients delived vaginally with intact membrane , the prevalence of histologic choriamnionitis tends to be higher in preterm (26.7%) deliveries(term 11.5% p=0.05). Conclusion : There was significant association between histologic choriamnionitis and preterm deliveries, and the degree of choriamnionitis was severe in ealier gestation. After controlling mode of delivery and labor, borderline association presisted between histologic choriamnionitis and preterm deliveries. Futher study will be needed.