The relationship between alkanol chain length and effects on the transient potassium current, IA, were examined in three identified Aplysia californica neurons with ethanol (EtOH), butanol (BuOH), and hexanol (HxOH). Qualitative differences were found when the actions of EtOH were compared with those of the longer-chain-length alcohols. Whereas EtOH primarily affected the decay time constant of IA, having minimal effects on amplitude, BuOH and HxOH exerted their major effect on the amplitude of IA, reducing it, while their effects on decay kinetics were much less pronounced. The effects of EtOH on IA decay are cell specific among identified neurons of the Aplysia nervous system. The actions of BuOH and HxOH did not mimic these interneuronal differences. These data, coupled with data previously reported by us and others, make it unlikely that EtOH exerts its actions on IA via perturbation of a bulk lipid phase within the membrane.