To compare maternal plasma LBP concentrations in pregnancies complicated by preterm premature rupture of membranes (pPROM), and PROM at term, with their levels in uncomplicated pregnancy, and to determine whether LBP concentrations are of value in the diagnosis of subclinical intra-amniotic infection (IAI) in the prediction of the length of the pPROM-to-delivery interval, and in the prediction of neonatal congenital infection.Thirty-one patients with pPROM, 35 with PROM at term, 33 healthy women at preterm gestation and 35 healthy women at term were included. In the pPROM group, analysis of maternal plasma LBP concentrations with reference to leukocytosis, C-reactive protein, vaginal fluid culture, neonatal infection and pPROM-to-delivery interval was carried out.LBP concentrations in the four studied groups were comparable. Although in 58.1% of pPROM cases at least one laboratory parameter of infection was observed, the only difference concerned the subgroup with CRP above 10mg/L, in which LBP concentrations were higher. Comparison of LBP concentrations in patients delivered within 24 and 72h of pPROM and after these times showed no differences, or between patients who gave birth to newborns with and without congenital infection. The predictive values of these measurements were poor.The predictive value of maternal LBP determinations in the diagnostics of pPROM cases suspected of IAI is unsatisfactory. LBP measurements performed shortly after pPROM, are not of value either in the prediction of newborn's infection, or in the prognosis of latency period duration.