Effects of some possible neurotransmitters such as GABA, adrenergic drugs, and 5-HT and their antagonists on the motility of Angiostrongylus cantonensis were studied. Paralysis was caused by GABA, avermectin BIa (Av-BIa), piperazine and alpha-adrenergic agonists such as adrenaline, noradrenaline, phenylephrine, clonidine and methoxamine, but not by beta-adrenergic agonists such as isoproterenol. The paralysis by GABA or Av-BIa was antagonized by GABA antagonists such as picrotoxin and/or bicuculline with cholinergic agents such as N-methylcytisine (N-MC) or eserine. The paralysis elicited by alpha-adrenergic agonists was antagonized by alpha-adrenergic antagonists such as phentolamine and dibenamine, but not by beta-adrenergic antagonists such as propranolol. 5-HT affected the motility of A. cantonensis paralytically or spastically. The paralysis induced by 5-HT was antagonized by alpha-adrenergic antagonists such as phentolamine and dibenamine, while the contraction induced by this compound was further stimulated by N-MC, but antagonized by strychnine. Other agents such as glutamine, glycine, aspartic acid, taurine, and substance P showed little effect on the motility of A. Cantonensis. From these findings on the neuropharmacological properties of A. cantonensis, it is suggested that this worm is useful as an excellent nematodal model for the investigation of anthelminthics. In addition, this worm may also useful as one of screening models of drugs affecting the central nervous system in mammals.