The objective of the present work was to study the influence of the application of the biological feedback (BFB) technique on the dynamics of the psychological and clinical status of the patients presenting with various chronic somatic diseases (CSD) and to identify the predictors of the effectiveness of the treatment by this method. The patients and methods. The study included 337 patients suffering from CSD who were interviewed with the use of the concise standardized multifactorial personality inventory (SMPI), the Spielberger State-Trait Anxiety Inventory (STAI), and the Beck depression inventory (BDI) scales. The patients were randomly distributed into two groups. Group 1 (main) was comprised of 168 patients who underwent psychotherapeutic treatment based on the BFB method, group 2 (control) consisted of 169 patients who did not receive the psychotherapeutic treatment. In order to identify the predictors of the effectiveness of the treatment by the biological feedback technique, the patients of the main group were subdivided into two subgroups at the end of the study period. Subgroup A contained 112 (67%) patients whose health status was normalized under the influence of psychotherapy, subgroup B included 56 (33%) patients who experienced the improvement of the somatic conditions. We undertook the comparative analysis of the background characteristics of the patients belonging to each group. Results and discussion. The study has demonstrated that by the end of the observation period the patients of the main group showed a significantly more pronounced (compared with controls) decrease of the parameters estimated based on the scales 1, 2, and 7 and an increase of those evaluated based on the (SMPI) scale 9. Simultaneously, the levels of state and trait anxiety estimated based on the Spielberger и Beck inventory scales decreased. These findings give evidence of the improvement of psychological adaptation of the patients, decrease of the anxiety level and emotional stress under the influence of the treatment with the use of the biological feedback technique; these changes were concomitant with the enhancement of the general activity of the patients, the improvement of their working capacity, mood, and feelings of optimism. The study of the predictors of the effectiveness of the BFB method revealed the significantly higher background values estimated based on the SMPI scales 1, 4, and 6 in the patients with the improvement of the health status compared with those exhibiting normalized conditions (p<0,01). In 12% of the patients in the former subgroup (but in none of the patients of the latter subgroup), the values obtained based on the Beck scale were higher than 20 scores which suggested either the moderate or high level of depression. These data give reason to conclude that the patients that exhibited a relatively weak response to the treatment with the application of the biological feedback technique were initially predisposed to the un-necessary excessive fixation of attention on their sensations in the combination with enhanced impulsivity, rigidity of attitudes, and the presence of depressive disorders.