Background: Despite the widespread use of continuous renal replacement therapy in critically ill patients with acute renal failure (ARF), there are few data supporting its benefits over conventional intermittent hemodialysis (IHD). We sought to analyze differences in survival between modalities in a study that compared continuous venovenous hemodialysis (CVVHD) with IHD. Methods: Eighty critically ill patients with ARF requiring dialysis were randomized after stratification by severity of illness to treatment with CVVHD or IHD. Results: There were no differences in survival or renal recovery between groups. In patients who died, mean survival time was 10.7 ± 11.2 days for the IHD group versus 14.3 ± 16.1 days for the CVVHD group (P = not significant). There was greater net volume removal in the CVVHD group during 72 hours. Declines in urine output during 72 hours were similar between groups. Mean arterial pressure off and on dialysis therapy was analyzed retrospectively. There was a significant decrease in mean arterial pressure for patients on IHD therapy not seen in those on CVVHD therapy, but this did not lead to a survival advantage. Conclusion: Despite greater volume control, CVVHD did not lead to an improvement in survival, preservation of urine output, or renal recovery compared with IHD in patients with ARF.