The presence of a functional nicotinic acetylcholine receptor (nAChR) in rat olfactory bulb (OB) neurons was investigated using the whole-cell patch-clamp technique. Acetylcholine (ACh) or other nicotinic agonists elicited fast-decaying whole-cell currents in cultured OB neurons. ACh-evoked currents could be blocked by the highly selective competitive nicotinic antagonists alpha-bungarotoxin (alpha-BGT, 10 nM) and methyllycaconitine (MLA, 1 nM) and exhibited strong inward rectification in the presence of intracellular Mg2+. The properties of the nicotinic currents in OB neurons were similar to those of type IA currents elicited by nicotinic agonists in rat hippocampal neurons. The present results suggest that the fast-decaying nicotinic currents evoked in OB neurons are subserved by nAChRs containing alpha 7 subunits.