Although subclavian vein stenosis is a well-known complication of haemodialysis subclavian catheters, little is known about its causes. Catheter-related infection is the most common complication of this technique, but its role in the genesis of late subclavian stenosis has not been established. We retrospectively analysed 80 subclavian catheterizations in a total of 54 chronic haemodialysis patients from a single center. Sixteen catheters had to be removed because of a well documented catheter-related infection: three catheter-related sepsis (2 with ipsilateral phlebitis), seven isolated fever with catheter tip colonization which disappeared after catheter removal, and six exit-site discharge with positive culture. For comparison we matched 14 contemporaneous catheters which were electively removed without evidence of infection and with a negative culture of the catheter tip. A venogram of the ipsilateral arm was performed in all the cases after more than 6 months of catheter removal. Both groups were remarkably similar with respect to age, sex, side of insertion, number of inserted catheters, time of indwelling, and time elapsed from removal to venography. Definite subclavian stenosis was three times more common among patients with previous catheter-related infection (75% versus 28%; P < 0.01). Interestingly, both patients with ipsilateral phlebitis showed total occlusion of the subclavian vein. Although all diabetic patients of the study (n = 6) suffered a catheter-related infection, the incidence of late subclavian stenosis was not more common than in non-diabetic infected patients. In summary, subclavian haemodialysis catheter-related infection is a major risk factor for the development of late subclavian vein stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)