Iodine is one of the trace minerals besides manganese, selenium, copper and iron that are important nutrients required at small amounts for normal growth and development of the chicken embryo. In the current trail the effects of inovo injection of nano iodine (Nano-I) during early incubation on embryonic mortality, hatchability, chick quality and some anatomical parameters in broiler chickens were investigated. A total of 500 hatching eggs of Ross 308 broiler breeders were numbered and weighed (average 65±0.5g.) then incubated at 99.8^oF and 55% R.H. On the 7th day of incubation, eggs were candled, and infertile eggs were excluded. The fertile eggs were distributed into 4 treated groups (100 eggs/treatment) as follows; C: un-injected eggs (control); sham: amnion sac was penetrated by a needle only, and two injected groups with 0.05 and 0.1 ml of 0.9 % nano-I (T1 and T2, respectively). Results showed a highly significant increase in the total embryonic mortality during both the incubation and hatching periods, especially during the mid-stage of incubation (8 to18 days) in Nano-I-injected groups compared with control groups. Incubation period duration increased significantly in injected a group that was dose-dependent (487.2 and 504 hours in T1 and T2, compared with 480 and 472.2 hr. in sham and control groups, respectively). Tona score was significantly higher in control 94% compared with 92% in sham and 84% in nano-I injected eggs. While chick weight, chick length and yolk free body mass % (YFBM %) had no significant differences between all treatments. Some anatomical observations were noted among the treatments. Duodenum, pancreas, thymus, spleen, and bursa of Fabricius were more developed in chicks that hatched from 0.05 ml nano-I group compared with those injected by 0.1 ml nano-I or control groups and this is very evident in the thyroid glands. There is no significant difference between treated groups in plasma level of T4 while nano-I injected groups were higher in plasma level of T3. It is concluded that; in ovo injection with nano-I at doses of 0.05 and 0.1 ml had a negative effect on hatchability and embryonic viability without significant effects on chick quality except for Tona score. More studies are needed to determine the optimal dose of nano-I for in ovo injection in broiler chickens.