Many North American refiners are looking to the Canadian oil sands as a plentiful hydrocarbon resource in the face of dwindling supplies of conventional crude oils.  However, the oil sands bitumen presents a number of challenges, even after it has been diluted to mimic traditional crudes for transport from Alberta to the United States.  As bitumen-derived crude oils become a larger portion of the refinery feedstock slate, more vacuum gas oil and heavy coker gas oil will be fed to the catalytic cracker to convert these heavy fractions to gasoline and distillate-range materials.  Gas oil hydrotreating may be required in order to obtain suitable cat cracker conversions and yields.  This paper will describe the results of pilot-scale hydrotreating and cat cracking studies conducted on straight-run vacuum and heavy coker gas oils isolated from Canadian bitumen-derived crude oils.