κ-Bungarotoxin is a high affinity antagonist of nicotinic acetylcholine receptors (nAChRs), particularly of CHRNA3; it causes a post-synaptic blockade of neurotransmission.

[3] κ-Bungarotoxin was first reported in 1983 as a component of the venom of Bungarus multicinctus that differed in biological effect from the previously known α-bungarotoxin: κ-bungarotoxin, but not α-bungarotoxin, was capable of impeding nicotinic signaling in the chick ciliary ganglion.

[4] Bungarotoxin toxin was designated "kappa" as an allusion to the Latin word kiliaris ("from the eye"), and to the root of "ciliary".

Two distinct binding surfaces, both on the N-terminal extracellular face of the receptor subunit, have been identified.

Like the α-bungarotoxins, κ-bungarotoxin causes a post-synaptic blockade of signaling; this is in contrast to the β-bungarotoxins which induce a pre-synaptic block.