An activated charcoal haemoperfusion device containing 300 g acrylic hydrogel coated activated charcoal, was combined with haemodialysis, on six occasions in each of two patients, for a 2-hour portion of a routine 5-hour dialysis schedule. Blood pressure changes with combined treatment were minimised by using a low priming volume dialysis filter. Plasma clearance of both creatinine and urate were increased during the combined haemodialysis-haemoperfusion period. During the two hours of the combined treatment period in one patient creatinine removal amounted to 70% and urate removal to 50% of that obtained during a 5-hour haemodialysis. No significant additional urea or phosphate removal occurred. Changes in middle molecular weight substances with combined treatment were slightly greater than changes occurring with dialysis alone. Haemodialysis alone did not result in a terminal platelet fall, but combined treatment resulted in a terminal 20-30% platelet reduction, despite unchanged platelet counts at the end of the 2-hour haemoperfusion period. This preliminary study suggests that combined haemodialysis-haemoperfusion, is worthy of further scrutiny.