It is presumed that adjuvant therapy rather than new antibiotics will improve the prognosis of pneumococcal meningitis. We investigated the effect of fucoidin, a polysaccharide inhibiting leukocyte rolling, on inflammatory changes in experimental meningitis in rats. After induction of meningitis by pneumococcal cell wall components, regional cerebral blood flow and intracranial pressure increased over the observation period of 6 h. At the end of the experiments, cerebrospinal fluid pleocytosis and brain water content were higher in animals with meningitis than without. Fucoidin treatment in the meningitis group reduced all inflammatory changes, whereas fucoidin treatment of animals without meningitis increased blood white cell count, but had no effect on any other parameter. Our results confirm that selectins are involved in the early phase of pneumococcal meningitis and possibly are a target for adjunctive therapy.