Techniques used for closure of the hysterotomy site following cesarean delivery include the use of interrupted, locked, and unlocked continuous sutures with single-or double-layer closure. The specific technique used may be associated with risk of uterine rupture during a trial of labor (TOL) in future pregnancies. In a recent systematic review, single-layer closure but not double-layer closure was shown to reduce operating time and blood loss. However, a large randomized controlled trial published in 2010 found no such benefit for single-layer closure. This systematic review and meta-analysis compared the effect of single-versus double-layer closure on risk of uterine rupture. A search of the electronic databases-PubMed, Embase, and Cochrane Central Register of Controlled Trials-was conducted to identify relevant citations published up to 2010 that included data on women with a previous single, low, transverse cesarean delivery who underwent TOL. Both observational and experimental studies were included in the search. To assess the risk of uterine rupture and uterine dehiscence, random effects models were used to calculate pooled odds ratios (ORs). Data from 9 studies including 5810 women met inclusion criteria for the meta-analysis. There was no statistically significantly higher overall risk of uterine rupture during TOL after use of a single-layer closure compared with a double-layer closure; the OR was 1.71, with a 95% confidence interval [CI] of 0.66-4.44 (P = 0.27). Compared with a double-layer closure, the use of a locked single-layer closure (OR, 4.96; 95% CI, 2.58-9.52, P < 0.001) but not an unlocked single-layer closure (OR, 0.49; 95% CI, 0.21-1.16, P = 0.1) was associated with increased risk of uterine rupture. These findings show that the risk of uterine rupture in women attempting a TOL is significantly higher with use of a locked single-layer closure than either an unlocked single-layer closure or a double-layer closure.