Five types of angiographic catheters used in current radiological and haemodynamic clinical practice at Sacré-Coeur Hospital in Montreal were studied for their mechanical sturdiness, and also with respect to the possibility that re-use could be associated with blood contamination by loose particles. Samples were taken both from new catheters and from catheters re-used up to 10 times. Routine cleaning and sterilization procedures showed no adverse effects on the maximum tensile strength and elongation at break of catheters. While some biological debris were occasionally present in re-used catheters, they appeared to be firmly fixed to the lumen surface, and they seemed unlikely to be carried into the blood stream during catheterization. On the other hand, new catheters exhibited a substantially higher loose particicle count than catheters which had been properly cleaned and sterilized. It is concluded that properly handled re-used angiographic catheters are just as safe for the patient as new catheters. The limit on the number of re-uses may depend on the care taken to avoid damage to the lumen surface during cleaning, on ageing on the catheter material and on economic considerations.