A starting assistance method and device for an internal combustion engine supplied with a fuel that may contain ethanol, and including a fluid connection pipe between an intake manifold and a braking assistance device. The method including determining the engine temperature, determining the outdoor air temperature, blocking the pipe between the intake manifold and the braking assistance device for a given duration during a phase of starting the engine when the temperature of the engine is lower than a first threshold value and the outdoor air temperature is lower than a second threshold value, and freeing the pipe between the intake manifold and the braking assistance device when the engine is rotating autonomously.