This paper reports the results of a pharmacological survey of drug action on muscle preparations of the anthozoan Bunodosoma caissarum. A critical review of previous results of drug action on Coelenterate neuromuscular junction is also given. The preparations responded only to body wall homogenates and acetylcholine. Sympathomimeticamines (adrenaline and nor-adrenaline), indolalkylamines (tryptamine, serotonin) and other drugs (tyramine, histamine, 1-glutamate and GABA) showed no action. The view that the Coelenterates do not employ acetylcholine as a neurotransmitter is discussed.