Prior pancreatic ductal ligation is a simple and effective experimental method for prolonging survival after a lethal dose of abdominal X-irradiation in dogs. In contrast to the usual average survival time of four days in lethally irradiated controls, survival times up to 153 days were achieved in animals with prior pancreatic ductal ligation. In 13 animals, the average survival time was 38 days. It is theorized that neutralization of intraintestinal proteolytic enzymes to decrease mucosal damage may prove useful clinically in enteropathies of varying etiological patterns.