Many authors demonstrated beneficial role of some acute phase proteins in response to tissue damage due to inflammatory reaction, injury or infection. Relationship between acute phase protein concentration and intensity of pathologic process has been demonstrated. The aim of the study was to evaluate serum α1-antitrypsin (AAT) concentration in patients with denture stomatitis as well as in healthy subjects. AAT concentration was measured by radial immunodiffusion method using NOR Partigen plates manufactured by Behring (USA). Study results showed highly significantly increased concentration of plasma AAT in denture stomatitis patients in comparison to the controls. Plasma α1-antitrypsin concentration in patients with severe, diffuse inflammation in oral mucosa over denture foundation area was highly significantly higher than in moderate, local inflammation group and than in the group of patients with hyperplastic lesions.