The procedure of peritoneal dialysis has emerged as a boon for patients with severe chronic kidney disease. This book describes the developments and novel concepts introduced in recent years on peritoneal dialysis (PD) and its difficulties. This therapy involves a renal substitution peritoneal membrane through a semi-permeable barrier for solutes and liquids. The abdominal cavity along with all its components, immune system components, mesothelial cells, fat tissue and others are activated because of the PD fluids that, although become more biocompatible every time, induce formation of molecules with the local and systemic effects. Locally, there is a thickening of the peritoneal membrane finally resulting in its failure, where the trans-differentiation of mesothelial cells plays a vital role. Systematic activation of the abdominal cavity seems to be responsible for diabetes, renal bone disease pathway, atherosclerosis, hypertension and other diseases.