PURPOSE: Large ventral hernias can be associated with significant loss of domain, and preoperative Botulinum Toxin A (BTA) has been suggested as an adjunct therapy to minimize the effects of ventral hernia repair and facilitate fascial closure. However, there is often bias in studies involving BTA and its use is associated with significant cost and its efficacy remains unclear. METHODS: We systematically searched Medline, Embase, Cochrane, and ClinicalTrial.gov for propensity-score matched (PSM) studies comparing preoperative BTA and AWR with standard AWR for complex hernias. We pooled odds ratios (ORs) and mean differences with 95% confidence intervals (CIs) to assess outcomes, applying a random-effects model. We used R studio version 4.3.1 for statistical analyses. RESULTS: We included six studies with PSM comprising 851 patients undergoing AWR. The mean age was 60.5 years, mean BMI was 31.8 kg/m CONCLUSIONS: Preoperative BTA did not offer significant benefits in AWR of complex incisional hernia repairs. However, TSA showed that the required sample size was not achieved.