The blood brain barrier (BBB) is a complex structure that separates brain interstitial fluid from blood. BBB dysfunction is a key feature of Central Nervous System diseases. This in vivo study examines the effects of Intravenous Immunoglobulin (IVIg), regularly used to treat immune and inflammatory diseases, on BBB function following LPS-induced BBB disruption. The change in permeability of the BBB was evaluated by MRI, using gadolinium. Our results suggest that LPS breach the integrity of the BBB with regional specificity and can be reversed by IVIg administration.