Avian infectious bronchitis (IB) was initially considered to be a disease primarily of the respiratory and female reproductive tract of chicken. Avian infectious bronchitis virus has wide and variable tissue tropisms. The important variant 4/91 strain has been isolated from the broiler breeder flocks. The Massachusetts serotype has been isolated in the epididymal region of the rooster reproductive tract. No detailed information is apparently available about the tropism of 4/91 strain of AIBV to the rooster reproductive tract. Therefore, we hypothesized that the rooster reproductive tract is a target for 4/91 strain. This study confirms that IBV 4/91 strain has a potential to infect the testicular tissue in rooster.