Device for extracorporeal blood treatment comprising: - a filter 102 having a primary and a secondary chamber separated by a semi-permeable membrane, - a withdrawal line connected to the primary chamber of the filter, - the withdrawal line operationally associated to a first means for regulating blood flow rate Qb, - a return line at the outlet of the primary chamber of the filter, - a first pre-infusion line connected to a local anticoagulation substance container and connected to the withdrawal line, and operationally associated to a second means for regulating anticoagulation liquid flow rate Qpre1, - a first post-infusion line connected to a container of a solution at least partially restoring blood ionic balance for infusing the solution in the blood and operationally associated to a third means for regulating the ionic balance restoring solution flow rate Qpost1, - an effluent line connected at the outlet of the secondary chamber of filter, connected to a drain pipe and operationally associated to a fourth means for regulating liquid effluent liquid flow rate Qeff, and - a CPU including a first means programmed to receive the signal output by the first, second, third and fourth means for regulating liquid flow rate (115, 119, 121, 123), the CPU including second means programmed to control at least the third means for regulating the ionic balance restoring solution flow rate Qpost1 as a function of: - an input flow rate equal to blood flow rate Qb, plasma water blood flow rate Q pw, or plasma flow rate Q p, characterized in that the second means are programmed to control the third means for regulating the ionic balance restoring solution flow rate Qpost1 also as a function of: - the effluent liquid flow rate Qeff, and - the anticoagulation liquid flow rate Qpre1. - a filter 102 having a primary and a secondary chamber separated by a semi-permeable membrane, - a withdrawal line connected to the primary chamber of the filter, - the withdrawal line operationally associated to a first means for regulating blood flow rate Qb, - a return line at the outlet of the primary chamber of the filter, - a first pre-infusion line connected to a local anticoagulation substance container and connected to the withdrawal line, and operationally associated to a second means for regulating anticoagulation liquid flow rate Qpre1, - a first post-infusion line connected to a container of a solution at least partially restoring blood ionic balance for infusing the solution in the blood and operationally associated to a third means for regulating the ionic balance restoring solution flow rate Qpost1, - an effluent line connected at the outlet of the secondary chamber of filter, connected to a drain pipe and operationally associated to a fourth means for regulating liquid effluent liquid flow rate Qeff, and - a CPU including a first means programmed to receive the signal output by the first, second, third and fourth means for regulating liquid flow rate (115, 119, 121, 123), - an input flow rate equal to blood flow rate Qb, plasma water blood flow rate Q pw, or plasma flow rate Q p, - the effluent liquid flow rate Qeff, and - the anticoagulation liquid flow rate Qpre1.