Abstract: Galanthamine has been used in clinics for treatment of infantile paralysis, myasthenia gravis and other diseases. Recently, 19 alkaloids were isolated at this Institute from Lycoris squamigera Maxim, cultivated in China. Among these alkaloids were galanthamine and lycoramine and the content of the latter compound was found to be about 9 times that of the former. It is known that lycoramine is the dihydro derivative of galanthamine, but until now its pharmacologic action has received little attention. In the present paper some neuropharmacologic actions and toxicity of these alkaloids were described. Experiments carried out in vivo and in vitro showed that lycoramine hydrobromide possessed an inhibitory effect on cholinesterase, and its potency was weaker than that of galanthamine hydrobromide. In mice, rabbits and cats, galanthamine hydrobromide was 2-8 times more toxic than lycoramine hydrobromide. The therapeutic index of the two alkaloids was similar. These alkaloids were found to be easily absorbed from the gastro-intestinal tract. Pretreatment with atropine sulfate, scopolamine or diazyl () protected mice from death produced by a single subcutaneous injection of lethal dose of galanthamine hydrobromide, but did not antagonize the toxicity of lycoramine hydrobromide. In our experiments the pharmacologic actions of galanthamine prepared at this Institute resembled those of nivalin (galanthamine prepared in Bulgaria). It should also have practical value for clinical use.