The combined effect of ochratoxin A (at diet levels of 130, 305 and 790 ppb) and penicillic acid was studied in 100 broiler chicks. Serological investigations revealed significantly lower haemagglutination inhibiting antibody titers in the experimental chicks immunized with vaccine against Newcastle disease. A statistically significant decrease of the body weight and the relative weight of lymphoid organs as well as a significant increase of the relative weight of kidneys and liver were seen. The main degenerative changes were observed in the proximal convoluted tubules in kidneys and slight degenerative changes were found in the hepatocytes. Degenerative changes and depletion of lymphoid cells were observed in the bursa Fabricii, thymus, spleen and Peyer's patches of intestinal mucosa. Serum analyses revealed significant decreases of the total protein and cholesterol, and significant increases of the uric acid and glucose. Haematological analyses showed a slight anaemia, leucocytosis and slightly decompensated metabolic acidosis. A statistically significant protective effect of 5% total water extract of artichoke on humoral immune response (increase of haemaglutination inhibiting antibody titer), relative organ weight as well as on pathomorphological, haematological and biochemical changes induced by ochratoxin A, was established.