The elimination rate of iohexol, a non-ionic contrast medium, from the blood by hemodialysis, and the elimination rate of iohexol by a dialyzer were studied in 15 patients with chronic renal dysfunction who required angiography or enhanced CT. The elimination rate of iohexol was 19.8% at 15 min after the start of hemodialysis, 30.6% after 30 min, 44.2% after 1 hour, 62.1% after 2 hours and 72.9% after 3 hours. The dialyzer elimination rate was maintained at about 75% from 1 to 3 hours after the start of hemodialysis. If only about 70% of iohexol in the blood needs to be eliminated, hemodialysis for 3 hours with a blood flow rate of 120 ml/min and a dialysate flow of 500 ml/min using a 0.7 m2 cellulose triacetate membrane is sufficient.