Abstract: This paper describes that 3-methoxy-4-hydroxyethoxy benzaldehyde (M.H.B). Possesses anticonvulsant effect and slight depressant action on the central nervous system.The mediun convulsion dose (CD_50) of pentylenetetrazol by ip injection in mice was elevated by M.H.B., but it could not antagonize threshold-electroshock seizure in mice.The epiletic E.E.G. induced by pentylenetetrazol (20mg/kg i.v.) was protected by M.H.B.(50Omg/kg p.o.) in rabbits.In addition, M.H.B.(1055mg/kg p.o.) might prolong the sleeping time caused by thiopental sodium (25mg/kg i.v.).