The local and systemic release of thromboxane A(2), prostaglandin I-2, leukotriene B-4 (LTB(4)), tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) were studied before and after operation in 29 patients with acute and 22 with chronic posttraumatic osteomyelitis, Twenty patients without osteomyelitis, who underwent operations for fractures of the lower extremities, served as controls. Blood and tissue samples from the osteomyelitic and control groups were collected under defined conditions and mediators were determined by radioimmunoassay (thromboxane B-2, 6-keto-prostaglandin F-1 alpha, LTB(4)) or by enzyme-linked immunosorbent assay (TNF-alpha, IL-1 beta, IL-6, and IL-8). In addition, common parameters (leukocyte count, C-reactive protein, temperature) were measured. The best correlation with acute disease activity was given by TNF-alpha, IL-6, IL-8, and LTB(4). Plasma levels of these mediators in acute osteomyelitis were significantly increased compared to chronic osteomyelitis and to controls, respectively. Tissue samples from the osteomyelitic focus shelved significantly increased levels for IL-8, IL-6, TNF-alpha, IL-1 beta, and LTB(4) in acute osteomyelitis, whereas the values for TxB(2) and 6-keto-prostaglandin F-1 alpha were only slightly increased compared to the chronic osteomyelitis group, This study describes the local and systemic liberation of various mediators in acute and chronic posttraumatic osteomyelitis in detail for the first time and provides data for pre- and postoperative monitoring of disease activity and demonstrates new pathogenetic and therapeutic aspects of bane modulation in osteomyelitis.