A controversy has existed for several years concerning the physiological relevance of the nicotinic receptor measured by alpha-bungarotoxin binding. Using mice derived from a classical F2 and backcross genetic design, a relationship between nicotine-induced seizures and alpha-bungarotoxin nicotinic receptor concentration was found. Mice sensitive to the convulsant effects of nicotine had greater alpha-bungarotoxin binding in the hippocampus than seizure insensitive mice. The binding sites from seizure sensitive and resistant mice were equally affected by treatment with dithiothreitol, trypsin or heat. Thus it appears that the difference between seizure sensitive and insensitive animals may be due to a difference in hippocampal nicotinic receptor concentration as measured with alpha-bungarotoxin binding.