Gas-fuelled apparatus for cooking food, in particular gas-heated oven, comprising a combustion chamber, a flue gas outlet conduit and a cooking cavity, blowing means being arranged so as to be directed towards said combustion chamber, said blowing means being capable of circulating, in a substantially open circuit made up by said combustion chamber and said flue gas outlet conduit, a flow of ambient air, wherein, upon turning on the electric installation of the oven, any possible unburnt fuel gas is permanently evacuated from said combustion chamber. In a preferred manner, the chamber housing the burner is provided with at least an opening communicating with the atmosphere, which is adapted to provide a natural evacuation passage for unburnt combustible gases. The first ignition to the burner occurs after a pre-determined time of ventilation, subsequently to the ignition command delivered by an appropriate control arrangement, and the following ignitions occur immediately after said ignition command.