Infectious bronchitis is an acute viral disease with high contagious and mortality among chicks. Apparent symptoms of Infectious bronchitis in chicks are tracheal respiration and nasal discharges. The objective of this study was to assessment H120 vaccination efficacy on respiratory tract in Broiler Chickens. In this study, 60 Ross 308 commercial strain one-day old chicks free of mycoplasma galisepticum and mycoplasma synoviae were divided into two, control and treatment, groups and three sub groups of 10 chicks. The treatment sub groups were vaccinated against bronchitis on the first day. All of chicks were placed in the hatchery and 20 mL of 10% formalin. H120 lyophilized vaccine of massachoset strain prepared in Razi institute was used for vaccination. The results of the present study show that spraying form of vaccination has a high reaction. So it is recommended that this kind of vaccination is used carefully. In the present study the aftermath of H120 vaccine spray was observed and recorded during Histopathological studies.