Liver cuts were performed on 21 Mini- Lewe pigs and then closed with suture in one case, and by ultrasonic welding of Fimomed - Gelaspon conglomerate in the other. Macroscopic assessment in situ and the histological examination of cut out liver areas regularly showed perifocal inflammatory peritoneal reactions and abscess formation for the sutured regions. From a histological point of view the liver tissue in the regions subjected to ultrasonic treatment reacted more strongly than after suture, particularly in the form of lobule structure disturbances, focal hepatitis, hepatic duct proliferation and destruction, and cholangitis. All of these were limited to the immediate vicinity of the conglomerate with its fibrous demarcation, which remained identifiable until the end of the experiment after a year and a half. The experiments resulted in the sucessful closure of the liver wounds in all cases where ultrasonic welding of Fimomed - Gelaspon compound was used. Application to human medicine is, however, not yet justified.