Polyvinylchloride (PVC) is the most commonly used material for tubing in extracorporeal circulation. It is usually plasticized by the addition of di-2-ethylhexyl-phthalate (DEHP). The plasticizer is physically mixed into the PVC. The potential danger of DEHP migration into blood has been discussed. It has been suggested that the polyurethane (PUR) coating should reduce this transport. Eight different types of PVC tubing sets for hemodialysis were investigated for migration of DEHP. In general, they contained -40% by weight of plasticizer. It was shown that -60 mg placticizer could be extracted from complete tubing sets during a 6-h period. The release rate of DEHP from the PUR coating compared with PVC was increased. The results show that in contrast to previously published information, PUR coating of PVC tubing is not an effective method forreducing migration.