Objective. The inflammatory bowel diseases (IBD), Crohn’s disease (CD) and ulcerative colitis (UC) are chronic inflammatory conditions that affect the gastrointestinal tract. In regulation of this inflammatory process, Interleukin-6 (IL-6) has a major role. Overproduction of IL-6 by immunocompetent cells contributes to development of the inflammatory condition. Elevated levels of IL-6 in saliva could be expected, because the saliva-producing cells are part of the digestive system. Material and methods. IL-6 concentrations in saliva and plasma were studied in patients with CD (n = 15), UC (n = 7) and reference persons (RP) (n = 19) by use of an ELISA method. Results. A significant difference in saliva IL-6 concentration between CD patients (median 16.9 ng/L; p < 0.05) and RP (median 6.3 ng/L) was found. A significant difference in plasma IL-6 concentration between CD (median 10.3 ng/L; p < 0.001) or UC (median 7.8 ng/L; p < 0.001) and RP (median 0.8 ng/L) was observed. In patients with CD, plasma IL-6 correlated significantly with C-reactive protein (CRP) as well as albumin. In patients with UC, saliva IL-6 and plasma IL-6 correlated significantly with AI (activity index) scores as well as albumin. In patients with UC, a significant correlation between the saliva and plasma IL-6 concentrations was found. Conclusions. IL-6 was found in saliva in patients with IBD, documenting the general involvement of the gastrointestinal tract extending to the mouth cavity, and measuring IL-6 may be an additional method for evaluating and monitoring the disease activity. Objectives. The inflammatory bowel diseases (IBD), Crohn’s disease (CD) and ulcerative colitis (UC) are chronic inflammatory conditions that affect the gastrointestinal tract. In regulation of this inflammatory process, Interleukin-6 (IL-6) has a major role . Overproduction of IL-6 by immunocompetent cells contributes to development of the inflammatory condition. Elevated levels of IL-6 in saliva could be expected, because the saliva-producing cells are part of the digestive system. Material and methods. IL-6 concentrations in saliva and plasma were studied in patients with CD (n = 15), UC (n = 7) and reference persons (RP) (n = 19) by use of an ELISA method Concentration between CD patients (median 16.9 ng / L; p <0.05) and RP (median 6.3 ng / L) was found. A significant difference in plasma IL- UC (median 7.8 ng / L; p <0.001) and RP (median 0.8 ng / L) were observed. In patients wit h CDs, plasma IL-6 was significantly associated with C-reactive protein (CRP) as well as albumin. In patients with UC, saliva IL-6 and plasma IL-6 turned significantly with AI (activity index) scores as well as albumin. In patients with UC, a significant correlation between the saliva and plasma IL-6 concentrations was found. Conclusions. IL-6 was found in saliva in patients with IBD, documenting the general involvement of the gastrointestinal tract extending to the mouth cavity, and measuring IL-6 may be an additional method for evaluating and monitoring the disease activity.