A 79-year-old woman was undergoing chronic hemodyalysis. She received a continuous infusion of milrinone of 0.25 microg x kg(-1) x min(-1) for 77 hours, 0.2 microg x kg(-1) x min(-1) for 39 hours and 0.1 microg x kg(-1) x min(-1) for one hour due to heart failure after mitral valve repair. While receiving continuous infusion of milrinone, she was undergoing continuous venovenous hemofiltration. After infusion of milrinone for three days no arrhythmia was seen except atrial fibliration, but blood pressure remained low. After stopping infusion of milrinone, the plasma concentration of milrinone was 792.7 ng x ml(-1) (therapeutic plasma concentration: 100-200 ng x ml(-1)). Now few data are available regarding the pharmacokinetic of milrinone in patients with severe renal failure and during CVVH. Therefore we should design a dose modification for intravenous milrinone in renal failure patients.