Objective. To study parameters of innate and adaptive immunity in the blood serum of patients with nonpsychotic mental disorders and to classify them by risk of psychosis manifestation. Material and methods. Authors studied 49 male patients, aged from 16 to 25 years, with nonpsychotic mental disorders corresponded to the premanifest stage of endogenous psychosis. The activity of leukocyte elastase (LE), functional activity of alpha-1-proteinase inhibitor (1-PI) and the level of autoantibodies (aAB) to S-100 and basic myelin protein were measured. Results. A significant increase in LE and 1-PI was found in patients compared to controls (p<0.001). The level of aAB to neuroantigens was similar in patients and controls. The increase in LE activity was positively correlated with HAM-D depressive symptoms and SOPS total scores (r=0.47, p=0.02). Correlations between 1-PI activity and scores on SOPS positive subscale (r= -0.61, p=0.002) and SOPS total scores (r= -0.43, p=0.04) were identified. After treatment, the improvement of patient's state assessed by SOPS and HAM-D was correlated with the decrease in LE activity in 80% (p<0.01). The further increase of LE activity in 20% may be considered as an indicator of low quality remission and risk of psychosis manifestation. Conclusion. Patients with nonpsychotic mental disorders with higher levels of inflammation markers may be attributed to high risk group.