It is widely believed that premature rupture of membranes accelerates fetal pulmonary maturity. The purpose of our study was to determine the duration of the latent phase, in the cases of premature rupture of membranes, required to achieve this effect. Retrospective analysis of our database yielded a group of 42 patients, who were delivered between 26 and 34 weeks gestation. The results of this study suggest that pulmonary maturation continues but is not accelerated after premature rupture of membranes. Delaying delivery for more than 72 hours after rupture of membranes is more likely to result in chorioamnionitis than accelerated pulmonary maturation.