Balloon deflation in long-term indwelling urinary catheters has been reported, and can necessitate a premature replacement of the catheter. This problem is studied in catheters of various materials and their performance in this respect compared. The catheters are also compared in terms of any change in effective shaft diameter. The results show that 100% silicone catheters perform significantly less well than silicone-coated latex ones on both parameters. The implications of these findings are discussed, and recommendations are made with regard to the selection of catheters for long-term use.