OBJECTIVE To document the efficacy of continuous arteriovenous hemofiltration with dialysis following renal failure, without protein restriction, and to explore the magnitude and clinical applications of total daily urea clearance. METHODS A noncomparative, descriptive account of a case series. Data were collected prospectively and analyzed retrospectively. METHODS A tertiary care facility in a statewide emergency medical services system. METHODS Twenty-eight patients with renal failure were supported by continuous arteriovenous hemofiltration with dialysis in a critical care unit during a 14-month period (21 patients with multitrauma; three patients with soft tissue infections; and four patients with multisystem organ failure who had been transferred from other hospitals). Renal failure was most commonly due to multisystem organ failure or associated with adult respiratory distress syndrome. RESULTS Continuous arteriovenous hemofiltration with dialysis days totaled 308 (mean 10.9). All patients received full protein alimentation (mean protein load 131 g/day). The blood urea nitrogen concentration was controlled, generally to 40 to 75 mg/dL (14.3 to 26.7 mmol/L) within 3 to 5 days. Total daily urea clearance ranged from 15 to 21 g/day. Five (18%) of the 28 patients survived. CONCLUSIONS Continuous arteriovenous hemofiltration with dialysis appears to be effective for the control of blood urea nitrogen and clearance of urea. This modality also permits full protein alimentation. Total daily urea clearance can be calculated easily and may have important clinical uses and implications.