A random clinical trial to compare two managements: a conservative one (experimental group) and an interventionist one (control group) in patients with PROM in pregnancy between 28 and 34 weeks, was carried out. A group of women with complicate pregnancies with PROM, with amniotic fluid index of 5 cm in four quadrants, and a negative amniotic fluid culture, by amniocenthesis; no antibiotics, were studied at Perinatology Department, Centro Médico Nacional, IMSS, Torreón, Coah. México, from November 1, 1992 to October 31, 1993. The latency period was longer in the experimental group, than the control group (7.9 and 3 days, p < 0.001). There were no difference in chorioamnioitis or endometritis in both groups (p > 0.1). There were five cases of mid RDS in the experimental group, and seven cases in the control group, and nine of severe RDS, all of them died; there was a highly significant difference in perinatal mortality, (p = 0.005). There were no differences in neonatal sepsis (p > 0.05). Adequate selection of patients for conservative management is safe for both, mother and newborn. Complications and death by sepsis were uncommon.