The role of adenovirus infection in the SARS is significant but every year this group of infections makes up to 30 % of general infectious morbidity. Nowadays features of nonspecific immune defence in patients with adenovirus infection are insufficiently studied. Particularly acute AVI problem appears to clinicians and scientists as a contagious disease, which is rapidly spreading in organized collectives, among military personnel, students. Purpose. To study the reactive response of polymorphonuclear granulocytes in the peripheral blood of adult patients with adenovirus infection. Materials and methods. 37 volunteers with SARS signs (Unified Protocol Criteria) were involved in this “case – control” type study. Absolute and relative quantities of the main immune cells populations in the peripheral blood were analyzed. Immunohematological indicators which characterize reactive response of the main non-specific immune cells were calculated. Clinical diagnosis was confirmed by the serological method of complement fixation test in paired sera and using adenoviruses common soluble complement-fixing antigen. Results. Neutrophil granulocytes reactivity increased by 83.92 % indicating these cells activation by cytokine system. The inflammatory process is accompanied by an increase in leukocytes absolute count – 19.76 %, band neutrophil leukocytes - in 2.18 times; lymphocytes – 30.30 % and monocytes – 48.15 %. Conclusions. Aforementioned means that there are different types of immune response to adenovirus infection antigens. Patients immune reactivity decreasing by 14.86 % means that specific immune response is formed later. Method of neutrophils reactive response evaluation can be used by practicing doctors for the early prediction of possible anti-infectious protection system alteration.