Background: Avian infectious bronchitis (IB) is a highly contagious and important respiratory disease with significant economic losses in the poultry industry. So far, several serotypes and genotypes of IB virus have been identified, which pose a problem in the prevention and control of the disease. The main way to control the virus is vaccination. One of the most common vaccines used in the country against this disease is the live attenuated H120 vaccine. Currently, the determination of the 50% infectious dose in SPF embryonated eggs (EID50%) is used to quantitatively evaluate and determine the titer of the virus for the purpose of vaccine formulation against infectious bronchitis. Objective: the aim of this study was to set up a rapid and sensitive method for quantitatively evaluate the dynamics of titer changes and the rate of virus replication in embryonated eggs, the Real-time PCR assay. Material and Methods: the assay was developed using a universal primer probe set and virus load was assessed in 12 hours intervals starting right after H120 vaccine virus inoculation in emberyonated chicken eggs up to 60hours post inoculation. Harvested allantoic fluids were investigated by classical EID50 method and molecular assay. Results: dynamic of virus load in both method was comparable in two method the lowest titer was at 12 hours and the highest load was detected at 24 and 36hpi.conclusion: the result of this study showed promising horizon for using molecular method instead of classic chicken emberyo infectious dose 50% which is already expensive and time consuming with high variables. Nevertheless real-time PCR is not approved in vaccine production it is suggested to apply this in-process control tests in order to expedite the H120 infectious bronchitis vaccine manufacturing process time and expenses plus insuring accurate and precise investigation.