Prevention of hepatitis B virus infection in transplant recipients can be difficult. Patients may be unresponsive to vaccination and intolerant of the intramuscular injections required to administer hepatitis B immune globulin (HBIG). A recipient of HBsAg-positive donor cells for a bone marrow transplant received multiple i.m. injections of HBIG. This mode of antibody delivery was limited by his thrombocytopenia and neutropenia and alternative forms of passive immunization were sought. Four lots of IGIV were investigated for anti-hepatitis B surface antibody (anti-HBs) content and all were found to contain significant antibody titer. Moreover, IGIV that was administered to four bone marrow transplant recipients for medical purposes unrelated to HBV transmission produced protective anti-HBs titers in all. These studies suggest IGIV may be useful for HBV prophylaxis in the appropriate setting or if HBIG is unavailable. The optimum regimen for HBV prevention in distinct transplant settings needs to be determined.