A novel endoscopic peroral transgastric approach to the peritoneal cavity was tested in a porcine model in acute and long-term survival experiments. Transgastric peritoneoscopy was evaluated in 50-kg pigs. After upper endoscopy, the peritoneal cavity was accessed by needle-knife puncture of the gastric wall, followed by extension of the incision either with a pull-type sphincterotome or by balloon dilation. The peritoneal cavity was examined, and a liver biopsy specimen was obtained. The gastric wall incision was closed with clips. Twelve acute and 5 survival experiments were performed. Both techniques of gastric wall incision were without complication. The acute experiments demonstrated the technical feasibility of the approach. In the survival experiments, all pigs recovered and gained weight. The peroral transgastric approach to peritoneal cavity technically is feasible and has the potential to be an alternative to laparoscopy and laparotomy.