A method that has proved to be the most sensitive approach for the early diagnosis of infection of the oral mucosa around dental implants has been used to monitor the exit-sites of percutaneous devices. For three months the state of the skin-catheter interface of 13 CAPD-patients was examined every four weeks. This examination included the measurement of pocket depth with the aid of a periodontal probe, the measurement of SFFR (sulcus-fluid-flow-rate) using standardized filter paper strips and a bacteriological swab of the exit-site. The results obtained demonstrated that SFFR can be measured around percutaneous implants. The measurement of SFFR appeared to be more useful in the monitoring of exit-sites of percutaneous devices than the measurement of pocket depth or the use of bacteriological swabs. Further studies for prolonged periods are necessary to determine whether measurement of SFFR can reliably predict onset of exit-site infection before clinical signs become evident.