An experimental study was conducted to investigate the relative permeability behaviour of a typical Canadian bitumen, water and gas. Series of isothermal core flood experiments were conducted on an unconsolidated core composed of cleaned Athabasca sand matrix and relative permeabilities of the involved phases were determined. Athabasca bitumen was used as the oil phase and distilled water and nitrogen were used as water phase and gas phase respectively. A vertical sand-pack core-holder of 1.5 inch diameter and 2 feet long was designed and fabricated to perform sequential injection of oil, gas and water at reservoir temperature and pressure, while collecting information on pressure drop across the core and fluid volumes. The history match technique was used to determine relative permeabilities for two-phase and three-phase water/oil/gas systems.