AFTER a series of Mann-Williamson dogs were treated with cortisone, it was noticed that when the animals were killed several weeks later there was a marked reduction in the number and extent of intra-abdominal adhesions compared to those in the controls or in animals treated with any other therapy or type of medication. Accordingly, the role of cortisone and corticotrophin (ACTH) in the prevention of experimental intra-abdominal adhesions was investigated. PROCEDURE Adhesions were produced in 30 mongrel dogs, 20 to 22 lb. (9 to 10 kg.) in weight, by sprinkling 0.25 gm. of talcum U. S. P. evenly over one side of the serosal surface of the small bowel and its mesentery from the ligament of Treitz to the cecum (method of Schiff, Goldberg and Necheles.1). Ten dogs were used as controls, 10 received 10 mg. of cortisone intramuscularly twice daily for two weeks, and 10 received 5 mg.