[en] Cross-bred Sprague-Dawley rats were subjected to percutaneous X-irradiation of the rectosigmoid using a split-dose regimen and focal dose of 50 Gy. One day as well as one, two and four months after the cessation of irradiation a termino-terminal anastomosis was established in the area exposed to radiation. On days, 3, 7, 14 and 21 after surgery those parts of the intestine, which had been united by anastomosis, were removed in order to determine the hydroxyproline content of the latter. Further determinations were made in specimens of the tissue 1 cm above the anastomosis and carried out before surgery, after intraperitoneal injection of the anaesthetic alone or in animals subjected to laparatomy including intestinal exposure, where no anastomosis was established. In general, the collagen levels determined in colon anastomoses of irradiated or non-irradiated intestines of rats did not point to any adverse effects from radiation on the healing process. This result appears to be largely consistent with the experiences so far gained at the clinical level in the preoperative irradiation of colon carcinomas. (orig./MG)