Background: Inhibition of angiogenesis is a major target in control and treatment of many disorders depend of angiogenesis. Chiton is a marine mollusk and it can be useful for treatment of diseases because of exist many chemical compositions in its. We investigated the effects of shell extract of chiton on angiogenesis in chorioallantoic membrane. Materials and Methods:In this experimental study, we used 30 Ross fertilized eggs that were divided into 3 random groups: control, sham-exposed (treated by dimethyle sulfoxide: DMSO) and experimental (treated with shell extract). In 2nd day, a window was opened on eggs in the sterile condition. Later, in 8nd day, a gelatin sponge appeared on chorioallantoic membrane and was soaked with 10 μL extract in treatment group and 10 μL DMSO in the sham-exposed group. In 12nd day, chorioallantoic membranes (CAMs) were photographed by research photo stereomicroscope in all cases. The numbers and lengths of vessels around the sponges were measured and compared with each other by SPSS-16 software and ANOVA (p<0.05). Results: The mean number of vessels (10.34±1.85) and length of vessels (13.12±2.04 mm) in the control group and mean number of vessels (9.97±1.38) and length of vessels (13.42±1.08 mm) in sham-exposed group was not any significant differences (p>0.05). There was a significant decrease in mean number of vessels (6.06±1.36) and length of vessels (9.76±1.21 mm) in experimental group. Conclusion: It seems shell extract of Chiton lamyican decreases the number and length of vessels around treated area so it can be used as inhibitory agent in treatment of angiogenesis dependent disease.