The study will look at the safety profile (unwanted effects) of the long-lasting anticoagulant PEG-hirudin (SPP200) and compare these unwanted effects to those of unfractionated heparin, commonly used in haemodialysis to avoid clotting of the graft and of the haemodialysis machine.

• Patients undergoing chronic haemodialysis via an arteriovenous graft
• Arteriovenous graft in place for at least 3 months
• Duration of haemodialysis of at least 3 months, with 3 full dialysis sessions per week with a duration between 2 and 5 hours per session
• Women patients must be either postmenopausal for more than 1 year or, if of childbearing age, must use adequate contraception
• Women patients must have a negative serum pregnancy test within one week of randomisation
• Able to provide written informed consent prior to study participation