The objective of this study was to evaluate maternal temperature, heart rate, leukocyte count and C-reactive protein in the prediction of fetal bacteraemia and positive amniotic fluid cultures in 75 pregnancies complicated by preterm prelabor amniorrhexis. Cordocentesis and amniocentesis were performed and fetal blood and amniotic fluid were cultured for aerobic and anaerobic bacteria. Amniotic fluid was also cultured for Ureaplasma urealyticum and Mycoplasma hominis. Patients were classified into 3 groups: negative fetal blood and amniotic fluid cultures (group 1, n = 45); negative fetal blood but positive amniotic fluid cultures (group 2, n = 18), and positive fetal blood cultures (group 3, n = 12). In the groups with intrauterine infection compared to the non infected group, the median maternal temperature, leukocyte count and C-reactive protein were significantly higher. In groups 1, 2 and 3 the respective incidences of maternal pyrexia were 0, 7 and 16% and raised C-reactive protein 13, 28 and 33%. In pregnancies complicated by preterm prelabor amniorrhexis, maternal temperature, heart rate, leukocyte count and C-reactive protein do not provide sensitive prediction of intrauterine infection.