Nineteen patients with pancreatitis and 40 with pancreatic carcinoma were examined for certain immunological characteristics (immunoglobulins, immune complexes, PHA-induced lymphocyte proliferation) and for the level of carcinoembryonic antigen (CEA) and CA 19-9 depending on blood bilirubin. Hyperbilirubinemia was identified in 21 patients with carcinoma and in 3 suffering from pancreatitis. Both patients' groups manifested an increase of the IgA level. Especially high characteristics were seen in hyperbilirubinemia. The level of other class immunoglobulins and immune complexes did not depend on blood bilirubin. The patients demonstrated suppression of PHA-induced lymphocyte response by autologous plasma, with more remarkable suppression being observable in hyperbilirubinemia. The level of CEA or CA 19-9 was increased in 89% of the patients with pancreatic carcinoma and in 30% of pancreatitis patients. No relationship was recorded between the level of oncofetal antigens and blood bilirubin.