The　present　paper　aims　at　an　upscaled　description　of　solute　concentration　transport　processes　in　countercurrent　dialyzer　systems　by　means　of　a　porous　media　approach　based　on　the　volume　averaging　theory.　In　consideration　of　solute　diffusion　and　ultrafiltration　processes,　a　general　set　of　upscaled　solute　concentration　transport　equations　has　been　derived　for　the　three　phases　in　a　hollow　fiber　dialyzer,　namely,　the　blood,　membrane　and　dialysate　phases.　Moreover,　the　corresponding　closure　problems,　which　can　be　solved　to　obtain　the　effective　properties　in　the　upscaled　model,　are　proposed.　For　the　one-dimensional　case,　analytical　expressions　of　solute　concentrations　in　both　blood　and　dialysate　phases　are　achieved,　so　as　to　elucidate　the　influences　of　ultrafiltration　flow　rate　and　distribution　coefficient　on　both　clearance　enhancement　and　solute　concentration　variations　along　the　length　of　dialyzer.　The　results　show　that　both　ultrafiltration　flow　rate　and　distribution　coefficient　have　no　significant　effects　on　solute　concentration　variations　along　the　length　of　dialyzer.　Nevertheless,　the　clearance　enhancement　are　found　to　have　linear　relationship　with　both　ultrafiltration　flow　rate　and　distribution　coefficient.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.