The nature of the surface of the used material is determining the complication rate in medium and long term application of nephrostomy and bladder catheters as well as ureteral splints. Tubings made of 8 different materials were irrigated for one to three weeks by means of an urolithic simulator, the pH-values from 5.8 to 7.0. Scanning electron Microscope showed good values with respect to silicon elastomer, teflon and ethylenacrylicacid copolymer. Considering technical and economical factors it seems to be proven that silicon elastomer and polyurethane are the most appropriate materials for splints and catheters, whereas rubber and PVC are less suitable for long time application.