Some of heavy oil reservoirs under solution gas drive show abnormally high final recoveries. One of the mechanisms to explain these phenomena is the foamy oil flow effect which occurs under a certain combination of capillary, viscous and gravity forces. It has been studied extensively, yet remains poorly understood and difficult to model. The objective of this work was to investigate the effect of oil foaminess on the performance of solution gas drive in heavy oil reservoirs.In this research, the first step was to find a foaming agent that will have a measurable effect on foam stability of a viscous mineral oil. An experimental procedure was developed to quantify the oil foaminess in the presence of added foaming agent. Several depletion tests were conducted with the added foaming agent at different depletion rates using a 2 meters long sand-pack. The experimental results showed that the foam stability had a positive effect on the solution gas drive performance. Such positive effects of enhanced oil foaminess were mainly observed at low depletion rates. It appears that foam stability plays an active role in the gas-phase build up during solution gas drive and the resulting production behavior.