The present study was performed to investigate the sedative effects of the combined administration of phenolic compounds. 4-hydroxy-3-methoxybenzaldehyde, a component of Gastrodia elnta, showing positive GABAergic neuromodulation was administered intraperitoneally together with an identical dose of 2,3-dihydroxybenzaldehyde, a potent antioxidant, to the rats and then evaluated for its effects on the convulsion, the hypnosis, the inxiety and the muscle relaxation. Combined administration of both compounds significantly reduced the pentyleneterazole-induced lethality. In addition, this mixture significantly enhanced the pentobarbital-induced sleeping time. Contrary to the anticonvulsive and sedative effects, the combined administration did not exhibit anxiolytic or muscle relaxant activities. These results indicated that the combined treatment of 2,3-dihydroxybenzaldehtyde and 4-hydroxy-3-methoxybenzaldehyde with different effects leads to the anticonvulsion and/or sedation