A method of filling a disposable electronic cigarette cartridge with a liquid substance; the method comprising the steps of: feeding the disposable cartridge along a filling path by means of a conveyor; and feeding the liquid substance downwards into the disposable cartridge at a feed station located along the filling path and by means of a feed device; the method further comprising the steps of: fitting the disposable cartridge, at a coupling station located along the filling path, upstream from the feed station, with a metering chamber, which is placed on top of the disposable cartridge, is of sufficient volume to contain a full measure of the liquid substance, and has a bottom outlet conduit terminating inside the disposable cartridge; feeding the liquid substance into the metering chamber at the feed station and by means of the feed device, so that the liquid substance falls by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge; waiting until all the liquid substance has fallen by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge; and removing the metering chamber from the disposable cartridge, at a removal station located downstream from the feed station and by means of a removing device, once all the liquid substance has fallen by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge. feeding the disposable cartridge along a filling path by means of a conveyor; and feeding the liquid substance downwards into the disposable cartridge at a feed station located along the filling path and by means of a feed device; the method further comprising the steps of: fitting the disposable cartridge, at a coupling station located along the filling path, upstream from the feed station, with a metering chamber, which is placed on top of the disposable cartridge, is of sufficient volume to contain a full measure of the liquid substance, and has a bottom outlet conduit terminating inside the disposable cartridge; feeding the liquid substance into the metering chamber at the feed station and by means of the feed device, so that the liquid substance falls by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge; waiting until all the liquid substance has fallen by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge; and removing the metering chamber from the disposable cartridge, at a removal station located downstream from the feed station and by means of a removing device, once all the liquid substance has fallen by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge. fitting the disposable cartridge, at a coupling station located along the filling path, upstream from the feed station, with a metering chamber, which is placed on top of the disposable cartridge, is of sufficient volume to contain a full measure of the liquid substance, and has a bottom outlet conduit terminating inside the disposable cartridge; feeding the liquid substance into the metering chamber at the feed station and by means of the feed device, so that the liquid substance falls by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge; waiting until all the liquid substance has fallen by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge; and removing the metering chamber from the disposable cartridge, at a removal station located downstream from the feed station and by means of a removing device, once all the liquid substance has fallen by gravity from the metering chamber, along the outlet conduit, into the disposable cartridge.