Background and purpose:Arsenic trioxide(As_(2)O_(3)) injection actually has an effect on solid tumors such as hepatoma in the clinic.In order to find out its mechanism of action,we studied the action of arsenic trioxide injection on angiogenesis of chick embryo chrioallantoic membrane(CAM).Methods:The effect of arsenic trioxide injection on angiogenesis was investigated by CAM model and computer image analysis.Results:Administered at three different concentrations of arsenic trioxide injection at 10,20 and 40,3 days later,the vessel area were 25.66%?4.17%,24.74%?2.54% and 21.51%?6.70%,respectively.Compared to the NS control group(vessel area was 30.68%?(4.64%)),there was an obvious difference(P0.05 among the three different concentration groups).Conclusions:arsenic trioxide injection has a strong inhibitory effect on angiogenesis,which may be used in suppressing cancer angiogenesis.