The invention relates to a device for the filtration of a complex fluid composition such as blood, characterised in that the device includes a base (12) with a bottom (18), a head (14) with a bottom (30), and a membrane (16) provided between said base and said head in order to define a lower chamber (C1) and an upper chamber (C2), an inlet tapping (26) for the complex composition to be filtered opening into said lower chamber (C1), an outlet tapping (28) for the retentate with flow adjustment means and opening into said lower chamber (C1), and an outlet tapping (36, 36-1) from the upper chamber (C2), wherein said outlet tapping (36, 36-1) for the permeate is subjected to a negative pressure.
