Many countries in the world contain significant heavy oil deposits. In reservoirs with viscosity over several hundred mPa.s, waterflooding is not expected to be successful due to the extremely high oil viscosity. However, in many smaller, thinner reservoirs, or reservoirs at the conclusion of cold production, thermal enhanced oil recovery methods will not be economic. Waterfloods are relatively inexpensive and easy to control; therefore, they will still often be employed in high viscosity heavy oil fields. This paper presents experimental findings of waterflooding in laboratory sandpacks for two high viscosity heavy oils of 4,650 mPa.s and 11,500 mPa.s at varying water injection rates. The results of this work show that capillary forces, which are often neglected due to the high oil viscosity, are important even in heavy oil systems. At low injection rates, water imbibition can be used to stabilize the waterflood and improve oil recovery. Waterflooding can therefore be a viable non-thermal enhanced oil recovery technology, even in fields with very high oil viscosity.