An apparatus for the extracorporeal treatment of blood with veno-venous access, of the type comprising a circuit defined by a main pump (2) and by one or more conduits through which the blood to be treated passes at a given flow value (V1), said circuit being provided with an oxygenator (4), which performs a treatment on the blood at a first flow value, and of a hemofilter (7), which performs a treatment on the blood at a second flow value, lower than said first flow value. The apparatus is characterized in that: said oxygenator (4) is arranged and acting on a first portion (21) of the blood circuit and that the hemofilter (7) is arranged and acting on a second portion (22) of the blood circuit arranged parallel to the first portion (21)； said second portion (22) is connected to the first portion.
