Abstract In order to meet the world's increasing demand for energy, petroleum producing companies must search for oil and gas in increasingly hostile environments. One area that shows great promise is in the deep water areas of the U.S. Gulf of Mexico. This is evidenced by increased lease sales and drilling activity that has occurred there within the last few years. As drilling moves into deeper waters, new technologies must be developed for safe and successful operations. Beginning around 1996 four projects were begun to develop dual gradient drilling, DGD, technology for use in water depths greater than 5000 ft. The four projects are Shell Oil Company's project1, the SubSea MudLift Drilling Joint Industry Project2, SMD, the Deep Vision project3, and Maurer Technology's Hollow Glass Spheres project4. Several publications have discussed the advantages that dual gradient drilling technology has over conventional deepwater drilling in the ultra-deepwaters.5,6,7 Although the advantages of the dual gradient projects are well documented, there has been little published on one of the major concerns expressed by all four projects. That is, how will well control differ for dual gradient drilling as compared to conventional riser drilling?6,8,9 This paper reports on a comparison of the well control aspects of dual gradient drilling to those of conventional riser drilling. It is based upon the work that the authors performed as part of the SMD project.