Nitrogen is very difficult to remove from natural gas. Most specifications require no more than 4% nitrogen or total inerts in the interstate pipeline system. With about 15% of the raw natural gas produced in the United States having nitrogen contents over 4%, technology is needed to economically bring the gas to pipeline quality. Cryogenic distillation, the current state-of-the-art technology, is expensive, especially in smaller applications. Lean oil systems, such as AET’s Mehra Process, and pressure swing adsorption processes, such as Nitrotech’s carbon molecular sieve and Engelhard’s Molecular Gate, are being applied in very limited cases. Membranes are in the development stage for such applications.