Aim of the study: paraclinical characteristics in patients suffering from active and inactive duodenal ulcer. Materials and methods. 78 patients with active duodenal ulcer and with inactive disease have been examined paraclinically. The patients’ age was from 25 to 60 y.o., middle age was 39.40±1.27 y.o. Men — 54 (69.2%), women — 24 (30.7%). All examined persons were divided into two groups based on peptic ulcer exacerbation or remission. The paraclinical examination included electroencephalography, reoencephalography. Results. The rheographic indexes showed the predominant complication of venous outflow in patients with duodenal ulcer both in the carotid and in vertebral-basilar basins, a predominant increase in artery tone of all calibers with reduced blood filling in the anterior circulation and in the vertebrobasilar basin. The definitive dynamics of changes in rheoencephalography indexes were noted in the patients with active peptic ulcer disease. In particular, a tendency towards the venous outflow and tone normalization, increase in blood filling in the anterior circulation and in vertebrobasilar basin, and some improvement in the intracerebral ratio of blood filling was determined. The changes detected by us on the electroencephalography suggest that the autonomic dysfunction in duodenal ulcer is a consequence of the functional disintegration of brain nonspecific limbic-reticular systems. In the course of treatment there was observed the regression of bioelectric activity disorganization and decrease in beta activity level, density of delta and theta rhythms, that pointed at harmonizing effect on the brain diencephalon-stem structures. Conclusions. The studied paraclinical characteristics can be used to clarify the somatoneurological relationships in duodenal ulcer and to improve diagnostic approaches in duodenal ulcer patients.