Meningoencephalitis remains a devastating disease with high morbidity and mortality. Despite advances in antibiotic treatment and critical care, mortality rate in bacterial meningoencephalitis is close to 25%. Moreover, neurological and neuropsychological sequelae emerge in up to 50% of survivors. Adverse outcome is significantly associated with events secondary to meningitis and damage of the blood-brain barrier. Several studies conducted on animals confirmed that matrix-metalloproteinases (MMP), a family of enzymes with major actions in the remodeling of exracellural matrix components facilitate this process which results in acute neurological complications. Gelatinases (MMP-2, MMP-9), the most complex family member, through degradation of gelatine and collagen IV play an important role in the pathogenesis of brain's inflamatory diseases (e.g. Guillian-Barre syndrom) and contribute to spreading the disease beyond the central nervous system. Infection (bacterial, viral or fungal) can lead to increased concentration and activity of metalloproteinases due to excessive enzyme's secretion or decrease in level of its natural inhibitors. A detailed analysis of those enzymes could help in developing new diagnostic and prognostic markers for meningoencephalitis and could facilitate new treatment approaches.