The invention provides a hemodialysis system comprising a dialyzer, a blood pump and a blood cassette (150) including a rigid housing (172), the housing (172) including a blood pump line (166) operatively connected to the blood pump for pumping blood through the blood cassette (150), the housing (172) further including a from-patient port (176), a to-patient port (178), a saline port (180), a to-dialyzer port (182) and a from-dialyzer port (184).