Abstract: Fifteen fractions were separated from the crude venom of Ophiophagus hannah on CM-cellulose 11 column chromatography with ammonium acetate buffer by 2-stage gradient elution and purified on Sephadex G-50 column. Among them, four fractions (Ⅷ. Ⅸ, Ⅻ and ⅩⅢ) showed high lethality. These four fractions were tested in experiments, unlike cobra venom and some other elapid venoms, and exhibited no cardiotoxic and presynaptic activities. They blocked the neuromuscular transmission of the isolated chick biventer cervicis muscle and inhibited its response to Ach, but not the response to KC1. The neuromuscular block produced by fractions Ⅻ, ⅩⅢ and Ⅸ was reversible and that by fraction Ⅷ was irreversible. The Ach release on the nerve terminal was not affected and Ach dose-response curve was shifted parallelly to the right by fractions Ⅷ and Ⅸ. It is concluded that these four fractions may be regarded as postsynaptic neurotoxins.