Two antisera prepared against the nicotinic acetylcholine receptor (nAcChoR) from Electrophorus exhibit comparable ability to inhibit high-affinity alpha-bungarotoxin binding to membrane fractions from rat brain or muscle, PC12 or TE671 cells, or Torpedo electric tissue. Only one of several monoclonal antibodies raised against nAcChoR from Torpedo inhibits toxin binding to membranes from rat brain or muscle or TE671 cells, but is considerably more potent as an inhibitor of toxin binding to Torpedo nAcChoR. These results indicate that some antibodies prepared against nAcChoR from electric tissue recognize epitopes near the high-affinity toxin binding sites. Some of these toxin binding site epitopes are preserved across species and tissues. The positive outcome of this study supports the continued use of toxin as a probe for at least a subset of mammalian neuronal nAcChoR.