With World oil demand increasing in the face of limited supplies, increasing attention is turning towards non-conventional oil sources as a means to relieve the pressure exerted on conventional stocks. However, non-conventional oils are hard to extract, process and transport. Several technologies are already at work with differing levels of success, recovery ranging from as low as 5% through to more than 70%. This paper reviews the range of Enhanced Oil Recovery techniques, broadly classified into either thermal or non-thermal methods, and their applicability to the extraction of heavy oils and bitumens. Advantages and disadvantages are presented in terms of their recovery factors, requirements, limitations and economics. The potential benefits of additional downhole catalytic upgrading of heavy oils are also explored.