A survey of 97 elderly catheterized patients revealed the catheter-related problems of leaking, blocking, need for irrigation, odour and irritation. Details were taken of factors thought to be related to the problems and the data were analysed by using stepwise forward multiple regression. Hospital and community patients were found to have different problems. Females in both groups had more problems than males. For hospital patients, larger catheters were found to be associated with most problems, particularly leaking and blocking. For community patients, immobility and daily changing of drainage bags were major problem causers. The common nursing practice of changing to wider-diameter catheters in an attempt to prevent bypassing is wrong.