To assess the state of the hepatobiliary system in psoriasis andpsoriatic arthritis in order to establish a causal relationship and to identify clinical and functional predictors of psoriatic disease progression. The study includedpatients with extensive psoriasis vulgaris (n = 175) aged 18 to 66 years old and healthy donors (n = 30), matched by sex and age: Group 1--patients with psoriasis (PS, n = 77), group 2--patients with psoriatic arthritis (PsA, n = 98), group 3--control. The evaluation of functional state of the hepatobiliary system was performed by the analysis of the clinical and anamnestic data and by the laboratory-instrumental methods. We identified predictors of psoriasis: triggers (stress and nutritionalfactor), increased total bilirubin, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transferase, eosinophilia, giardiasis, carriers of hepatitis C virus, ductal changes andfocal leisons in the liver, thickening of the walls of the gallbladder detected by ultrasound. Predictors ofpsoriatic arthritis: age over 50 years, dyspeptic complaints, the presence of hepatobiliary system diseases, the positive right hypochondrium syndrome, the clinical symptoms of chronic cholecystitis, excess body weight, high levels of bilirubin, cholesterol and low density lipoprotein, hepatomegaly, non-alcoholic fatty liver disease. High activity of hepatocytes cytolysis, cholestasis, inflammation, metabolic disorders let us considerpsoriatic arthritis as a severe clinical stage psoriatic disease when the hepatobiliary system, in turn, is one of the main target organs in systemic psoriatic process. Non-alcoholic fatty liver disease and chronic cholecystitis are predictors of psoriatic disease progression.