Two patients with Hickman catheters that were used for long-term venous access developed major venous thrombosis, one with superior vena caval and the other with subclavian vein thrombosis. This represented an incidence of 9% of all Hickman catheters that were inserted over two years in The St George Hospital. Staphylococcus epidermidis was cultured from blood that was sampled through the Hickman catheter in both patients; the organism was also cultured from the tip of the removed catheter in one patient. Transverse thoracic computerized tomographic scanning diagnosed the presence and the site of thrombosis as well as excluding the presence of a mediastinal tumour that was causing extrinsic compression. The catheter had to be removed in one patient; in the other patient, heparinization without removal resulted in the resolution of symptoms.