Abstract: A refillable ink cartridge for removable connection to a print head of an inkjet printer. The ink cartridge comprises at least one ink chamber comprising side walls and a bottom wall. A cover hermetically seals the ink chamber or chambers by forming a top wall therefor. Each ink chamber has a tube associated with it, the tube extending from the cover into the ink chamber and comprising a continuous opening extending from an upper to a lower end of the tube. The opening at the lower end of the tube is associated with a valve to enable the opening to be opened and closed to controllably admit air into the ink chamber. The ink cartridge further comprises an ink supply port through which ink is supplied to the print head via an ink supply needle.