Abstract. With the use of 6% dextran solutions in saline as a dialysis fluid, a normal effect is observed with regard to extraction of nitrogenous products. The 6% dextran solution has a feeble dehydrating effect, and as a result of the lack of buffers there is no correction of acidosis. The clinical use of dextran solution for dialysis is mainly restricted to diabetic patients without acidosis and uraemic patients with abnormal carbohydrate metabolism. The dialysis should not be continued for long periods because of accumulation of dextran in the body. The composition of a new dialysing fluid is suggested.