A blood purification system has a primary purification device (32) and receives, at an input via a primary inlet line (31), a primary input fluid from a fluid source. The primary purification device (32) partitions the input fluid into two output streams. The first output stream (33) is enriched in larger components and the second output stream (34) is enriched in smaller components. The first output stream is returnable to the source via a primary outlet line (33). The secondary purification device (36) receives fluid from the primary purification device (32) and partitions the fluid into two further streams: a third output stream (37) enriched in larger components and a fourth output stream (39) enriched in smaller components including toxins and incidental beneficial molecules. The third output stream (37) is directed to flow to the sink (38). A tertiary purification device (40) receives the fourth output stream (39) and purifies the fourth stream from toxins. The purified fourth stream merges with either the primary inlet line (31) or the first output stream (33). As a result, a wide spectrum of blood borne toxins is removed from the source, including small molecular weight toxins, albumin saturated with toxins, defective forms of albumin, albumin bound and unbound toxins, middle size toxins, inflammatory mediators and mediators of unwanted biological responses, while, at the same time, the volume of wasted fluid and losses of incidental beneficial molecules are reduced.Linvention concerne un système de purification du sang comprenant un dispositif de purification primaire (32) et recevant, au niveau dune entrée par un tuyau dadmission primaire (31), un fluide dentrée primaire provenant dune source de fluide. Le dispositif de purification primaire (32) divise le fluide dentrée en deux courants de sortie. Le premier courant de sortie (33) est enrichi en composants plus gros et le deuxième courant de sortie (34) est enrichi en composants plus petits. Le premier co
