In peritoneal dialysis (PD), the frequent exposure to dialysis fluids elicits a chronic state of a low-grade peritoneal inflammation. On the morphological level, fibrosis and angiogenesis is common after chronic PD, as are abnormalities in the peritoneal membrane. In the long run, the dialysis capacity of the peritoneal membrane is lost due to these changes. Under isoflurane anesthesia, injection ports were implanted and attached catheters were tunneled to the peritoneal cavity. Treated group (PD; n=8) received PD twice daily, while catheter control group (CC; n=7) just had catheters and ports implanted. Negative controls received no treatment (NC; n=5). After 8 weeks, interstitial fluid (IF) from peritoneum was isolated using a centrifugation method and analyzed for cytokine content along with plasma. Collagen and hyaluronic acid (HA) was measured in the peritoneal tissue. The results showed a local production of TGF-b in peritoneal tissue in the PD group (p<0.05). VEGF was not changed due to PD. Collagen content in PD (p=0.03) and in CC (p=0.005) was higher as compared to NC. HA increased in PD (p=0.018), with a trend towards increase in CC (p=0.072) compared to NC. In conclusion, the local production of TGF-b in the peritoneal IF in response to chronic PD may be an integral component in the development of fibrosis. However, VEGF levels were generally low, and other mediators of angiogenesis may be involved in the process. The changes in the collagen and HA contents in CC indicate that the catheter per se may alter the extracellular matrix composition.