Introduction: Angiogenesis is a complex process. In fact, it is one of the most important biological events that can be observed with the production of new vessels in many stages of embryonic development and pathological conditions. In pathological conditions such as tumor growth, the progression of the disease is associated with angiogenesis. Therefore, in the present study, the effects of various doses of zinc oxide nanoparticles on chick chorioallantoic membrane (CAM) were assessed.
 
Materials & Methods: In this experimental study, 40 ROSS egg were randomly divided into four groups (controls-group 1-group 2-group 3). After the second day of incubation, a window was opened on the eggs and on the eighth day a gelatin sponge was placed on the chick chorioallantoic membrane. Experimental groups were treated with 500, 1000 and 2000 μg / ml zinc oxide nanoparticles, respectively. On the twelfth day after the incubation, samples were removed from the device and after removing the windows, all of them were viewed using a photo stereomicroscope.
 
Findings: The results showed that zinc oxide nanoparticles significantly reduced the number and length of blood vessels compared to the control sample (P <0.05). The mean length of blood vessels treated with nanoparticles of zinc oxide compared to the control group showed that there was a difference between the treated group with concentration of 500 μg / ml zinc oxide nanoparticle (3.16 ± 0.4 cm) with control group (4.13 ± 0.44 cm) at the level of P < 0.05 is significant.
 
Discussion & Conclusion: The results of this study showed that zinc oxide nanoparticles have anti- angiogenesis activity in an in vivo environment. In vivo studies showed that treatment with this nanoparticle inhibited angiogenesis would reduce the number and length of chick chorioallantoic membrane vein.