Flecainide, a new antiarrhythmic drug, has been shown not no be removed to a significant extent by hemodialysis or peritoneal dialysis, in spite of a high renal clearance. Its systemic and hemofiltrate clearances, measured in a patient under continuous hemofiltration, were 402 and 19.7 ml/min respectively. The clearance ratio of less than 5% makes the contribution of hemofiltration to the elimination of flecainide clinically negligible.