Abstract: The active ingredient of Huyinling, a combination of Chinese traditional medicine, was extracted by five different ethanol concentrations（40%-80%）. There were seven groups named as five Huyinling ethanol extract groups （40%, 50%, 60%, 70%, and 80%）, metronidazole group and blank control. Each Huyinling ethanol extract group was further divided into five subgroups with final concentration of 6.25, 12.5, 25, 50, and 100 mg/ml, respectively. Metronidazole group was given 10 μg/ml of the drug. Each group had 4 wells with 125 μl T. tenax（2×105/ml）. At 12 h, 24 h and 48 h after drug treatment, the anti-T. tenax effect of Huyinling ethanol extract was tested by microscope counting method. At 24 h the effect of Huyinling on T. tenax was examined with methyl thiazolyl tetrazolium （MTT） assay. The results showed that the higher concentration of Huyinling ethanol extract, the better effect on anti-T. tenax. 60% Huyinling ethanol extract group with concentrations of 6.25 mg/ml and 12.5 mg/ml showed higher anti-T. tenax effect than other groups （P<0.01）. The ethanol extract of Huyinling granules has a remarkable effect on T. tenax, and among the groups, 60% ethanol extract shows the best anti-T. tenax activity.

Key words: Huyinling, Trichomonas tenax, Chinese medicine