A new dialysis modality was devised to increase convective mass transfer. Blood and dialysate are circulated by a pulsatile pump, but with pulsatile flow patterns that are 180° out of phase, which causes blood-to-dialysate pressure gradients to oscillate between positive and negative. In the present study, hemodialytic performance of the devised modality was investigated using a canine renal failure model. Membrane hydraulic permeabilities (Kuf) and fiber bundle volumes (FBV) were measured after each dialysis session. Postdialysis Kuf and FBV were then compared with those with conventional high-flux hemodialysis. No complications concerning animals or technical problems with the devised modality were encountered. Urea and creatinine reductions were satisfactory. Postdialysis Kuf and FBV values were significantly reduced after hemodialysis sessions, but were higher for the new modality. The devised modality incorporated with blood and dialysate pulsation offers a simple but safe means new mode of hemodialysis.