A method to control a wastegate valve in an internal combustion engine turbocharged by means of a turbocharger provided with a turbine and with a compressor; the internal combustion engine comprising an intake manifold and an exhaust manifold and being suited to allow air to directly flow from the intake manifold to the exhaust manifold; the method comprises the steps of: determining an objective supercharging pressure (P obj); measuring an actual supercharging pressure; determining, in a design phase, a control law, which provides an objective opening of an actuator controlling the wastegate valve as a function of the mass flow rate (M R), preferably the reduced mass flow rate, of the compressor and, selectively, as a function of the objective compression ratio (RP obj) resulting from the ratio between the objective supercharging pressure (P obj) and the pressure upstream of the compressor or of the compression ratio resulting from the ratio between the actual supercharging pressure and the pressure upstream of the compressor; determining a first open loop contribution (WG OL) of an objective position (WG obj) of the actuator controlling the wastegate valve by means of the control law, which is a function of the objective compression ratio (RP obj); determining a second closed loop contribution (WG CL1) of the objective position (WG obj) of the actuator controlling the wastegate valve by means of the control law, which is a function of the compression ratio; calculating the objective position (WG obj) of the actuator controlling the wastegate valve by adding the first open loop contribution (WG OL) and the second closed loop contribution (WG CL1); and controlling the actuator controlling the wastegate valve so as to pursue the objective position (WG obj) of the actuator controlling the wastegate valve; the control method is characterised in that the step of determining, in a design phase, a control law, which provides an objective opening of an actuator controlling the wastegate valve, comprises the sub-steps of: determining a contribution (WG NOSCAV) of the objective position (WG obj) of the actuator controlling the wastegate valve in the absence of air directly flowing from the intake manifold to the exhaust manifold; determining a contribution (WG SCAVeff) of the objective position (WG obj) of the actuator controlling the wastegate valve, which indicates the quantity of air directly flowing from the intake manifold to the exhaust manifold; and determining the first open loop contribution (WG OL) of an objective position (WG obj) of the actuator controlling the wastegate valve and/or the second closed loop contribution (WG CL1) of the objective position (WG obj) of the actuator controlling the wastegate valve by means of the algebraic sum of the contribution (WG NOSCAV) in the absence of air directly flowing from the intake manifold to the exhaust manifold and of the contribution (WG SCAVeff) indicating the quantity of air directly flowing from the intake manifold to the exhaust manifold. determining an objective supercharging pressure (P obj); measuring an actual supercharging pressure; determining, in a design phase, a control law, which provides an objective opening of an actuator controlling the wastegate valve as a function of the mass flow rate (M R), preferably the reduced mass flow rate, of the compressor and, selectively, as a function of the objective compression ratio (RP obj) resulting from the ratio between the objective supercharging pressure (P obj) and the pressure upstream of the compressor or of the compression ratio resulting from the ratio between the actual supercharging pressure and the pressure upstream of the compressor; determining a first open loop contribution (WG OL) of an objective position (WG obj) of the actuator controlling the wastegate valve by means of the control law, which is a function of the objective compression ratio (RP obj); determining a second closed loop contribution (WG CL1) of the objective position (WG obj) of the actuator controlling the wastegate valve by means of the control law, which is a function of the compression ratio; calculating the objective position (WG obj) of the actuator controlling the wastegate valve by adding the first open loop contribution (WG OL) and the second closed loop contribution (WG CL1); and controlling the actuator controlling the wastegate valve so as to pursue the objective position (WG obj) of the actuator controlling the wastegate valve; determining a contribution (WG NOSCAV) of the objective position (WG obj) of the actuator controlling the wastegate valve in the absence of air directly flowing from the intake manifold to the exhaust manifold; determining a contribution (WG SCAVeff) of the objective position (WG obj) of the actuator controlling the wastegate valve, which indicates the quantity of air directly flowing from the intake manifold to the exhaust manifold; and determining the first open loop contribution (WG OL) of an objective position (WG obj) of the actuator controlling the wastegate valve and/or the second closed loop contribution (WG CL1) of the objective position (WG obj) of the actuator controlling the wastegate valve by means of the algebraic sum of the contribution (WG NOSCAV) in the absence of air directly flowing from the intake manifold to the exhaust manifold and of the contribution (WG SCAVeff) indicating the quantity of air directly flowing from the intake manifold to the exhaust manifold.