Background: EW-7197 is an oral transforming growth factor β type I receptor kinase inhibitor currently undergoing phase I clinical trials for cancer treatment in the United States. This study evaluates whether EW-7197 prevents peritoneal adhesion formation in a rat model. Methods: Forty-eight female Wistar rats underwent peritoneal adhesion induction by the creation of peritoneal ischemic buttons and were randomly divided into 4 groups of 12 each. The control group received 0.3 mL vehicle by oral gavage once daily for 7 days after adhesion induction. The 10 mg and 20 mg groups received 10 or 20 mg/kg EW-7197 phosphate dissolved in 0.3 mL vehicle by oral gavage once daily for 7 days after adhesion induction. The rebound group received 20 mg/kg EW-7197 phosphate dissolved in 0.3 mL vehicle by oral gavage once daily for 7 days after adhesion induction followed by 0.3 mL vehicle only by gavage once daily for an additional 21 days. After the respective treatments were completed, the animals were euthanized. Results: All rats survived until the end of the study without complications. EW-7197 reduced the incidence, quality, and tenacity of peritoneal adhesions in a dose-dependent manner. Fibrosis and collagen production were reduced in EW-7197–treated peritoneal ischemic buttons. Transforming growth factor β/Smad2/3 signaling and mesothelial-to-mesenchymal transition were inhibited in EW-7197–treated peritoneal ischemic buttons. Discontinuation of EW-7197 was not associated with rebound effects. Conclusion: EW-7197 prevented peritoneal adhesion formation potentially via inhibition of transforming growth factor β1/Smad2/3–induced mesothelial-to-mesenchymal transition in a rat model.