We evaluated the outcome of pregnancies complicated by preterm premature rupture of membrane (PROM) in order to determine if tobacco, alcohol, or illicit drug usage were associated with alterations in pregnancy or neonatal outcome. A retrospective study of patients with a gestational age Ͻ36 weeks admitted between 1993 and 1996 with PROM were evaluated for their clinical characteristics and pregnancy outcome. Comparisons in outcome were made with respect to tobacco, alcohol, and/or illicit drug usage. Comparisons were made with gestational age (GA) of PROM, GA of delivery, latency period (LP), maternal age, initial cervical exam (by speculum), age, race, tocolytic use, chorioamnionitis, and birthweight. Student's t-test, Mann-Whitney test, and Chi-square analysis were used to evaluate for significant differences (significance set at P Ͻ 0.05). A total of 119 charts were evaluated. Differences were noted with respect to smokers vs. nonsmokers for latency period (6.0 days vs. 9.4 days, P Ͻ 0.03), age (29.1 years vs. 24.8, P Ͻ 0.001), and gravidity (4.2 vs. 2.8, P Ͻ 0.005). Differences were noted for use of alcohol and age (29.9 vs. 25.2, P Ͻ 0.006). Differences were also noted for the use of illicit drugs and the following variables: age (30.0 vs. 24.9, P Ͻ 0.001), gravidity (4.7 vs. 2.5, P Ͻ 0.006), latency (6.2 vs. 9.0, P Ͻ 0.009), and parity (2.6 vs. 1.2, P Ͻ 0.01). A difference was noted with respect to cocaine and latency period (5.8 vs. 9.0, P Ͻ 0.01), age (31.2 vs. 24.8, P Ͻ 0.001), gravidity (4.8 vs. 2.9, P Ͻ 0.01), and parity (2.6 vs. 1.2, P Ͻ 0.03), and the use of tocolytics (22% vs. 55.4%, P Ͻ 0.02). These relationships held after multivariate analysis was performed. There were no associations among use of tobacco, alcohol, drugs of abuse, or cocaine and respiratory distress syndrome, intraventricular hemorrhage, or necrotizing enterocolitis. The use of tobacco during pregnancy appears to shorten the latency period in pregnancies complicated by PROM. Cocaine abuse also appears to shorten the latency period. These shortened latency periods could potentially contribute to increased neonatal morbidity. Larger studies evaluating this are needed.