Immunoglobulin therapy has been used for the treatment of primary and secondary antibody deficiency for more than 25 years. It is a safe preparation with no long-term side effect. Although the mode of action remains unknown, the drug is thought to have potent immunomodulating and anti-inflammatory actions. Recently we have found that immunoglobulin treatment is beneficial upon myocardial diseases and atherosclerosis. In basic aspects, immunoglobulin therapy for experimental myocarditis has been found to be effective not only by the Fab portion for anti-pathogen effects but by the Fc portion for antiinflammatory effects. Also, the drug was useful for the treatment of experimental atherosclerosis in apolipoprotein E-deficient mice. In clinical aspects, the effect of immunoglobulin administration for fulminant myocarditis and acute dilated cardiomyopathy was investigated. Immunoglobulin administration was very useful for the treatment of such patients. That is, although the study population was small, the drug showed the potential beneficial effects against active myocardial damage with myocardial dysfunction, and the left ventricular ejection fraction of the patients was recovered by the treatment. Accordingly, immunoglobulin treatment for patients with heart failure and atherosclerosis appears to be novel and effective treatment strategies.