Infection-mediated inflammation may be responsible for premature delivery in cases of preterm prelabour amniorrhexis. Histological examination of the cord and placenta was performed in 54 such pregnancies, in addition to amniocentesis and cordocentesis at presentation. Histological chorioamnionitis was more likely in those with positive amniotic fluid and/or fetal blood cultures, and in those cases with histological evidence of inflammation, the interval to delivery was short regardless of the culture results. Inflammation rather than infection per se may be the best indicator of preterm delivery in preterm prelabour amniorrhexis.