Tetramethylpyrazine is one of the alkaloids contained in Ligusticum wallichii FRANCH. Ferulic acid is a phenolic compound contained in Ligusticum wallichii FRANCH and Angelica sinensis (OLIV.) DIELS. The present study was carried out to examine the effect of tetramethylpyrazine and ferulic acid and the combined effect of both compounds on spontaneous uterine contractions in rats in situ. Tetramethylpyrazine and ferulic acid showed an inhibitory effect on uterine movement when given perorally and intravenously, respectively. The combination of both compounds, at doses individually insufficient to inhibit, synergistically inhibited uterine contraction.It was found taht tetramethylpyrazine and ferulic acid inhibited uterine contractions and the inhibitory effect induced by the combination of both was due to the potentiation.