Simulated maxillary sinusitis was observed in guinea pigs following the surgical incision in superior cervical sympathetic ganglion. Additionally, toxic hepatitis development was stimulated after exposure to tetrachlormethane in experimental animals. The treated and control animals were observed for three months. A significant increase in the content of reactive oxygen species [ROS] in neutrophils and lymphocytes was noted in artificially developed sinusitis. The ROS values were slightly higher in the case of combined experimental sinusitis and toxic hepatitis. Based on the obtained data, the role of ROS in the development of sinusitis was discussed.