BACKGROUND Prelabour rupture of the membranes at or near term (term PROM) increases the risk of infection for the woman and her baby. The routine use of antibiotics for women at the time of term PROM may reduce this risk. However, due to increasing problems with bacterial resistance and the risk of maternal anaphylaxis with antibiotic use, it is important to assess the evidence addressing risks and benefits in order to ensure judicious use of antibiotics. This review was undertaken to assess the balance of risks and benefits to the mother and infant of antibiotic prophylaxis for prelabour rupture of the membranes at or near term. OBJECTIVE To assess the effects of antibiotics administered prophylactically to women with prelabour rupture of the membranes at 36 weeks or beyond, on maternal, fetal and neonatal outcomes. METHODS We searched the Cochrane Pregnancy and Childbirth Group's specialised register of controlled trials (October 2001), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 4, 2001), MEDLINE (1965 to 2001). Other sources included contacting recognised experts and cross referencing relevant material. METHODS All randomised trials which compared outcomes for women and infants when antibiotics were administered prophylactically for prelabour rupture of the membranes at or near term, with outcomes for controls (placebo or no treatment). METHODS Assessment of trial quality and data extraction were undertaken independently by the two authors who then compared and resolved differences. Additional data were received from the investigators of included trials. Meta-analysis was undertaken using a fixed effects model and results are presented using relative risk (RR), risk difference (RD) and number needed to treat (NNT) (where appropriate) for categorical data, and mean difference (MD) for variables measured on a continuous scale. All results are presented with 95% confidence intervals (CI). RESULTS The results of two trials, involving a total of 838 women, are included in this review. The use of antibiotics resulted in a statistically significant reduction in maternal infectious morbidity (chorioamnionitis or endometritis): RR 0.43 (95% CI 0.23, 0.82), RD -4% (95% CI -7%, -1%), NNT 25 (95% CI 14 -100). No statistically significant differences were shown for outcomes of neonatal morbidity. CONCLUSIONS No clear practice recommendations can be drawn from the results of this review on this clinically important question, related to a paucity of reliable data. Further well designed randomised controlled trials are needed to assess the effects of routine use of maternal antibiotics for women with prelabour rupture of the membranes at or near term.