A system to control the injection of gas (1) into an underground burrow (2) occupied by pest rodents (3), the system comprising a gas supply system (4), which is configured so as to supply a gas mixture, an injector (5), which is structured so as to be at least partially fitted inside the burrow (2), and is configured to receive the gas mixture supplied by the gas supply system (4) so as to inject the gas mixture received into the burrow (2) itself and an electronic control system (6), which is configured so as to determine the concentration of at least one component of the gas mixture injected into the burrow (2) and to control the gas supply system (4) so as to vary the quantity of gas mixture supplied to the injector (5) based on the concentration of the component that has been determined.
