Four lavandulyl flavanones, (2S)-2'-methoxykurarinone (1), sophoraflavanone G (2), leachianone A (3), and (-)-kurarinone (4), which are isolated from the roots of Sophora flavescens have been tested for in vitro antimalarial activity against Plasmodium falciparum. Compounds 1-3 showed moderate antimalarial activities with EC(50) values of 2.4 x 10(-6), 2.6 x 10(-6), and 2.1 x 10(-6) M, respectively. These compounds did not show selective toxicity against P. falciparum in the toxicity test on mouse mammalian tumor cells, however, it is suggested that the position of methoxyl groups in flavanone skeleton plays an important role on antimalarial activity.