An aim of the study was to investigate the psychopathological structure, pathopsychological mechanisms of the formation and predictors of depressive disorders in Parkinson's disease (PD), taking into consideration the form, stage, progression rate and severity of motor symptoms, and to develop a system of differential therapy. Along with general clinical and psychopathological examination, a complex of psychometric and psychodiagnostic methods was used. Three variants of depressive disorders were singled out: adaptation disorder (59 patients), prolonged depressive reaction; recurrent depressive disorder (36 patients), organic depressive disorder (89 patients). In total, 184 PD patients with depression disorders and 76 patients without depression were studied. History of disease, results of the clinical examination and changes in scores of psychometric and psychodiagnostic measurements as well as the results of differential pharmaco- and psychotherapy were considered for all variants.