FIELD: medicine. SUBSTANCE: method involves taking blood samples and determining IgG immunoglobulin in blood serum. Free SH-groups contents on erythrocyte membranes is additionally determined as related to erythrocyte mass. The ratio of free SH-groups contents on erythrocyte membranes related to erythrocyte mass and circulating IgG immunoglobulin contents is determined. Resistance coefficient value being greater than 0.09, premorbid state is to be diagnosed and development of nonspecific inflammatory diseases of catarrhal type is predicted with 95% probability level. EFFECT: high accuracy in predicting infectious inflammatory diseases development at preclinical stage. 2 tbl
