Saline solution amnioinfusion was performed for 12 cases of preterm PROM before 27 weeks gestational age complicated by oligohydramnios in order to suppress chorioamnionitis, prevent fetal pulmonary hypoplasia and delay delivery. The results were as follows. 1. The mean gestational ages at diagnosis of premature rupture of membranes and initiating saline solution amnioinfusion were 23.6 +/- 2.9 weeks and 24.9 +/- 1.5 weeks, respectively. The mean duration of saline solution amnioinfusion was 14.7 +/- 11.9 days. The mean gestational age at delivery was 27.2 +/- 1.7 weeks. The mean birth weight was 1,056 +/- 220g. 2. Saline solution amnioinfusion was effective in relieving oligohydramnios in all cases. No pulmonary hypoplasia was observed in the infants. 3. Clinically saline solution amnioinfusion was effective in suppressing chorioamnionitis in 9 cases out of 12. Histologically the picture of chorioamnionitis was revealed in 10 cases out of 12. no serious infection was observed in the infants. 4. Nine infants out of 12 survived. There were 2 IUFD and one neonatal death. The perinatal survival rate was 75%. 5. It is concluded from the above results that saline solution amnioinfusion is an effective treatment for preterm PROM before 27 weeks' gestational age.