Indomethacin (IN) has been reported to increase the risk of neonatal complications such as intraventricular hemorrhage (IVH) and renal failure. Recently other non-steroidal anti-inflammatory agents such as sulindac (SU) have been shown to be effective tocolytics, but the neonatal effects have not been described. Objective: investigate the outcome of infants born to mothers receiving IN and SU for tocolysis. Methods: Case control study of infants <1500g born 7/94-7/97 at a single level III NICU. Infants who received a minimum of one cranial sonogram were divided into 3 groups: those whose mother received SU (n=20), IN (n=39), and a control group who received neither drug (n=341). Multiple antenatal and postnatal factors were compared using ANOVA with post-hoc testing and multiple logistic regression analysis. Results: Infants in the IN group were of younger gest. age(26.7 ± 2.0 vs 28.6 ± 2.9 wks, p=.008) compared to controls. There was no difference in gestational age in SU (26.9 ± 2.5 wks) compared to IN or control. There was no difference in birth weight, IUGR, Apgar scores, c-section, or gender between groups. Infants in the SU and IN group were more likely to have been exposed to prenatal steroids (90% IN, 90% SU, 57% control, p<.01) and MgSO4 (74% IN, 80% SU, 31% control, p<.01) compared to controls. Infants in the IN group were less likely to have mothers with preeclampsia (3% vs 18%, p=.01), or premature rupture of membranes (18% vs 37%, p=.01) compared to controls. There was no statistical difference in the incidence of IVH, severe IVH, PDA, PDA needing surgical ligation, mortality, renal failure (serum creatinine >1.4mg/dl in the 1st week of life), NEC, PVL, sepsis or length of hospital stay between infants in the SU and IN group as compared to each other or the control group. On univariate analysis the IN group was more likely to develop BPD (75%) compared to SU (40%, p=.05) and control (41%, p=.01). The IN (92%) and SU group (95%) were both more likely to require mechanical ventilation compared to controls(74%, p=.03). However, after controlling for potential confounding variables by multivariate analysis, infants in the IN group did not have an increased odds of developing BPD (odds ratio, 1.9, 95% Confidence Interval,.7-5.3) and neither IN (OR 1.1,CI.3-3.8) or SU (OR 2.7,CI.5-14) were associated with an increased odds of requiring mechanical ventilation. Conclusions: In our population of infants <1500g, SU or IN do not increase the risk of serious neonatal complications including IVH, renal failure, PDA and BPD when given antenatally.