A gasoline internal combustion engine, comprising: - an engine block with a plurality of cylinders and a cylinder head defining a combustion chamber associated with each cylinder, and at least one intake duct and at least one exhaust duct, provided with respective intake and exhaust valves (7,8), associated with each combustion chamber, - a first spark plug associated with each cylinder, mounted within a support element, which is arranged within a seat of said cylinder head and which defines a combustion pre-chamber having a first end facing the electrodes of said first spark plug, and a second end communicating with the respective combustion chamber through a plurality of orifices, - a second spark plug associated with each cylinder, having electrodes directly facing the combustion chamber, - at least one electromagnetically-controlled gasoline injector device (16,17), associated with each cylinder of the engine, - an electronic control unit, configured to control said first spark plug, said second spark plug and said at least one gasoline injector device (16,17) for each cylinder of the engine, said engine being characterized in that: - said at least one gasoline injector device (16,17) comprises one gasoline injector device for injecting gasoline directly into the combustion chamber and/or one gasoline injector device for injecting gasoline into an intake associated with said cylinder, - no device for injecting gasoline or air or a mixture of air and gasoline directly into said combustion pre-chamber is associated with the combustion pre-chamber, - said electronic control unit is programmed to control said at least one gasoline injector (16,17) to produce an air/gas mixture in said combustion chamber, according to a ratio essentially corresponding to a stoichiometric dose, or a richer dosage than the stoichiometric dose, - said electronic control unit is programmed in such a way that said second ignition spark plug having electrodes directly facing the combustion chamber is only activated at low and medium engine loads to stabilize the combustion, and is inactive, or kept active but without any influence on the combustion, for example by activating it during the expansion or exhaust stage of the cylinder, at higher loads, - said combustion pre-chamber is dimensioned with a volume less than 0.5%, preferably less than 0.3%, of the capacity of the single cylinder of the engine, in order to reduce the detonation tendency of the engine at high loads. - an engine block with a plurality of cylinders and a cylinder head defining a combustion chamber associated with each cylinder, and at least one intake duct and at least one exhaust duct, provided with respective intake and exhaust valves (7,8), associated with each combustion chamber, - a first spark plug associated with each cylinder, mounted within a support element, which is arranged within a seat of said cylinder head and which defines a combustion pre-chamber having a first end facing the electrodes of said first spark plug, and a second end communicating with the respective combustion chamber through a plurality of orifices, - a second spark plug associated with each cylinder, having electrodes directly facing the combustion chamber, - at least one electromagnetically-controlled gasoline injector device (16,17), associated with each cylinder of the engine, - an electronic control unit, configured to control said first spark plug, said second spark plug and said at least one gasoline injector device (16,17) for each cylinder of the engine, - said at least one gasoline injector device (16,17) comprises one gasoline injector device for injecting gasoline directly into the combustion chamber and/or one gasoline injector device for injecting gasoline into an intake associated with said cylinder, - no device for injecting gasoline or air or a mixture of air and gasoline directly into said combustion pre-chamber is associated with the combustion pre-chamber, - said electronic control unit is programmed to control said at least one gasoline injector (16,17) to produce an air/gas mixture in said combustion chamber, according to a ratio essentially corresponding to a stoichiometric dose, or a richer dosage than the stoichiometric dose, - said electronic control unit is programmed in such a way that said second ignition spark plug having electrodes directly facing the combustion chamber is only activated at low and medium engine loads to stabilize the combustion, and is inactive, or kept active but without any influence on the combustion, for example by activating it during the expansion or exhaust stage of the cylinder, at higher loads, - said combustion pre-chamber is dimensioned with a volume less than 0.5%, preferably less than 0.3%, of the capacity of the single cylinder of the engine, in order to reduce the detonation tendency of the engine at high loads.