Abstract: A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is disclosed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The hydrate inhibitors used for practicing the method are substantially water soluble polymers formed from a N-substituted acrylamide having two nitrogen substituent groups, R.sub.1 and R.sub.2, where R.sub.1 is a hydrocarbon group having from one to ten carbon atoms and zero to four heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and combinations thereof, and R.sub.2 is a hydrogen atom or a hydrocarbon group having from one to ten carbon atoms selected from the group consisting of carbon, nitrogen, oxygen, and sulfur; alternatively, R.sub.1 and R.sub.