We have found that the pharmaceutical agent, gemfibrozil, already used in the human population to treat hyperlipidemia, protects a significant proportion of mice infected with influenza virus (H2N2) from developing a fatal disease (17) . Gemfibrozil belongs to the fibrate class of drugs, which, like statins, are used to lower blood lipid levels, although fibrates differ in their mechanism of action. Gemfibrozil is a synthetic ligand for the peroxisome proliferator activated receptor (PPAR) alpha. This nuclear receptor controls lipid homeostasis, with fatty acids and eicosanoids as endogenous ligands (18, 19) . We chose gemfibrozil for its known ability to reduce release of inflammatory cytokines, including TNF, interleukin (IL)-6 and interferon-g (IFN-g), as well its ability to inhibit the nuclear translocation of the transcription factor nuclear factor k-B (NF-kB) (20) (21) (22) , and hypothesized that these drug side-effects might be useful in ameliorating influenza disease, as has already been suggested (23) . We have found that the protective ability of gemfibrozil during influenza infections is likely to be a fibrate class effect, since fenofibrate also reduces the mortality of influenza virus-infected mice (unpublished data). Gemfibrozil lowers serum IL-6 levels in mice infected with influenza virus (unpublished data) but its effects on other aspects of the host immune response are not yet known, and remain the subject of our further study.