Simulated continuous arteriovenous hemodialysis (CAVHD) was performed with Renaflo anisotropic polysulfone capillary hemofilters and Biospal homogeneous PAN parallel-plate hemofilters. Inulin and glucose were present in the dialysis solution. Plasma and dialysis solution flow rates were varied as was the delivery of dialysis solution by gravity or pump. The presence of dialysis solution did not affect the components of transmembrane pressure and did not alter ultrafiltration rate. Inulin and glucose backtransported into the plasma perfusate during CAVHD with the Biospal but not with the Renaflo filters. Dialysis solution will need to be sterile and pyrogen-free even in the low-flow, low-pressure system of CAVHD.