Neurological deficit and alterations in the hippocampus still frequently occur following bacterial meningitis in children, despite the antibiotic treatment. We investigated the long-term outcomes using early versus late antibiotic therapy in experimental pneumococcal meningitis. To this aim, male Wistar rats underwent a basilar cistern tap receiving either sterile saline as a placebo or an equivalent volume of a Streptococcus pneumoniae suspension. Antibiotics were started 8 or 16 h after infection and the animals were followed for 10 days to the determination of long-term cognitive outcomes. The animals were submitted to the habituation of an open-field as an index of long-term cognitive function. Early antibiotic administration (8 h after inoculation) when compared to late antibiotic administration (16 h after inoculation) prevented cognitive impairment induced by pneumococcal meningitis in Wistar rats. The findings from this study suggest that early antibiotic administration is an effective strategy to prevent long-term cognitive impairment in a meningitis animal model.