Background: Intra-abdominal adhesions are fibrous bands that develop after abdominal surgery or inflammation and cause mortality and morbidity following surgeries. This study aimed to assess the effects of bupivacaine, saline and two doses of lidocaine, after peritoneal lavage and to compare their effects in reducing abdominal adhesions in rat. Methods: In a blinded, randomised, placebo-controlled clinical trial, 50 female rats were anaesthetised and the parietal peritoneum was scratched to induce punctate bleeding. The rats were randomly assigned to five groups: saline, lidocaine 2% (3 and 6 mg/kg), bupivacaine 0.25% (2 mg/kg) and control (no irrigation). The peritoneal cavity was irrigated with the appropriate solution during laparotomy. Two weeks later, re-laparotomy was performed. The quantity, quality, severity and scores of adhesions were recorded and compared. Results: The quantity and quality of adhesions were significantly higher in the control group than in the lidocaine (6 mg/kg) and bupivacaine groups. The quality of the adhesions was higher in the normal saline group than in the lidocaine (6 mg/kg) and bupivacaine groups. The severity of adhesions between the lidocaine 3 and 6 mg/kg groups and between the lidocaine 3 mg/ kg and saline groups was lower than that in the control group. Conclusion: Using lidocaine (6 mg/kg) and bupivacaine lavage in first laparotomy reduces abdominal peritoneal obstruction because of the formation of adhesion bands.