Pro- and antiinflammatory cytokines and mediators were measured in 39 patients with acute life-threatening meningococcal infections classified into 3 groups: A, meningitis without shock (n = 20); B, meningitis with shock (n = 9); and C, shock without meningitis (n = 10). The plasma concentrations of proinflammatory endotoxin, tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, and IL-8 and antiinflammatory cytokines and mediators IL-1 receptor antagonist, IL-10, and soluble TNF receptors p55 and p75 were strongly associated with this classification; the highest concentrations were in group C. IL-4 was not measurable. IL-1 beta was increased only in rapidly fatal cases. In addition, cerebrospinal fluid (CSF) was analyzed in 21 patients for TNF-alpha and its soluble receptors. In CSF, these compounds were mainly increased in group A, reflecting an intrathecal compartmentalized cytokine production. It is concluded that both pro- and antiinflammatory mediators are simultaneously increased and are strongly associated with a classification based on simple clinical parameters.