Abstract Many heavy crudes show foaminess at surface conditions. The foam formed is usually very stable and can remain in an open vessel for several hours. This stability is especially obvious when taking fluid samples from producing wells. The emphasis of recent research on "foamy" crudes has been on explaining the unexpectedly large recovery efficiencies of these crudes by solution gas drive (so-called cold production). This work studies a different aspect of these crudes, namely their ability to reduce gas production in light/medium oil wells. As far as we know, this is the first application of foamy crudes to reduce produced gas-oil ratio (GOR). If successful, the technology should be less expensive than polymer gel or foam treatments (the competing technologies for lowering GOR) because no formulation is needed and there are no expensive chemicals involved. The ability of foamy crudes to reduce gas production GOR is supported by experimental results. We conducted four experiments in sand packs under pressures and temperatures typical of Venezuelan light/medium crude oil reservoirs. The experiments were primary depletions done until a relatively large gas-oil ratio (GOR = 4000 scf/stb) was reached. At this point, we injected a slug of foamy crude through the producing side of the pack and continued the depletion. Slug sizes of the foamy crude ranged from 0.05 to 0.1 of pore volume. We monitored the experiments through the produced GOR, gas and oil rates and pressure profiles. The experiments showed dramatic declines of GOR, ranging from the starting value of 4000 scf/stb to almost to the solution gas-oil ratio measured at the existing pressure. This represents a GOR reduction of up to 96%. The average of all tests had an incremental oil recovery of 8% after the injection of the foamy crude. As a result of the lab experiments, we began a pilot test in a mature medium oil field (Acema 200, San Tomé, Eastern Venezuela). The slug size was 150 bbl of foamy crude, which penetrated an average of 12 ft into the reservoir. After one month of monitoring, this field test showed an incremental oil recovery of up to 2000 bbl and a GOR reduction of 80%. The oil production rate increased by 328%, therefore the application cost of 5500 $ US was recovered by the second day of production. We measured a sudden increase of the GOR 3-1/2 months after the heavy oil injection.