Chronic bacterial ulcers infection is a frequent cause of non-healing diabetic foot. The major factors of a non-specific immune response are phagocytic cells including polymporphonuclear (PMN) leukocytes, and humoral systems (complement). PMN leukocytes remove microorganisms by phagocytosis a part of it is intracellular killing and degradation in a process requiring energy and associated with "respiratory burst". The aim of our study was to assess non-specific immune response in patients with diabetic foot syndrome and chronic bacterial infection. 30 patients treated over one month with antibiotics for an infected diabetic foot in our foot clinic had significantly lower values of "oxidative burst" of PMN leukocytes in basal state (396 +/- 228 vs. 574 +/- 337, p < 0.05) in comparison with 25 matched healthy controls. There were no significant differences neither in the count of active phagocyting PMN leukocytes and their initial phagocytic activity nor in the humoral component of non-specific immunity (in circulating immunocomplexes, C3 and C4 components of complement) between both groups. The results of our study show a slightly altered non-specific immune response in patients with diabetic foot syndrome and chronic bacterial infection.