The inflammatory hypothesis of Alzheimer's disease states that specific inflammatory mechanisms, including the cytokine-driven acute-phase response, complement activation and microglial activation, contribute to neurodegeneration. If the hypothesis is correct, anti-inflammatory treatment aimed at suppression of these mechanisms could slow the rate of disease progression. Towards this goal, a multicentre trial of prednisone in Alzheimer's disease is under way and pilot studies of other anti-inflammatory regimens are being conducted.