Intraperitoneal hydrostatic pressure (IPP) was measured in 10 patients for 15 days (until day 15) following peritoneal catheter implantation. Tenckhoff catheters were surgically implanted using a transrectal approach. The patients began peritoneal dialysis (PD) immediately, initially with small intraperitoneal fluid volumes (500 mL), gradually increasing to reach 2000 mL by day 7. In one patient PD was delayed until day 7 because of an initial leakage of dialysate. Inspiratory and expiratory IPP were measured daily, with the zero point fixed at the midaxillary line with the patient in the supine position. Despite the small intraperitoneal fluid volumes used initially (500 mL), IPP was much higher in the first 3 days following implantation than in the next 12 days (17 +/- 3 cm of water vs 11 +/- 1 cm of water). IPP remained high until day 3, then gradually decreased in a linear fashion until day 12, despite the increased intraperitoneal volumes used, and then remained constant. In conclusion, IPP was found to be significantly higher for 3 days following intraperitoneal catheter implantation, whichever intraperitoneal volume was used. This may be due to tense abdominal muscles from pain caused by the surgery or because of reduced intraperitoneal compliance at the beginning of PD.