In 35 patients fulfilling the criteria of systemic inflammatory response syndrome (SIRS) of infectious origin, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), tumor necrosis factor-soluble receptor (TNF-sR), and interleukin-12 (IL-12), C-reactive protein (CRP) levels and the Acute Physiology, and Chronic Health Evaluation III score (APACHE III) were determined on days 1 to 7, 14, 21, and 28. The Mortality Probability Models (MPM) II sepsis score was assessed at the time of admission into the study. The MPM II sepsis score correlated with IL-6 plasma levels on day 1. The APACHE III scores correlated with plasma levels of TNF-sR on days 2-7, with IL-6 levels on days 3-7, and with CRP levels on days 4-7 (p < 0.01). The MPM II sepsis score, the APACHE III score, and the IL-6, TNF-sR, and CRP levels were significantly different between survivors and nonsurvivors and between patients with and without shock (p < 0.05). A significant decrease of the APACHE III scores, IL-6, and CRP levels was observed over the study period in the survivor group only (p < 0.05), while neither the dynamics of TNF-alpha nor IL-12 plasma levels contributed to the risk estimation of mortality.