Recent studies have demonstrated that commercial preparations of hepatitis B immune globulin often contain antibody to the human immunodeficiency virus. The presence of this antibody has aroused concerns that treatment with hepatitis B immune globulin might passively induce human immunodeficiency virus antibody seropositivity, leading to incorrect diagnoses of human immunodeficiency virus exposure. We studied a group of 16 normal volunteers who received an intramuscular dose of hepatitis B immune globulin (0.06 ml per kg) which was later discovered to contain human immunodeficiency virus antibody. None of the subjects had human immunodeficiency virus antibody before receiving hepatitis B immune globulin. Serum specimens collected at 1 to 4, 6, 8, 12, 16, 20 and 24 weeks after the injection were consistently negative for human immunodeficiency virus antibody. There was no detectable human immunodeficiency virus antibody in any specimen from any subject. We conclude that intramuscular therapy with hepatitis B immune globulin in the recommended dose does not appear to place patients at risk of passive seroconversion to human immunodeficiency virus antibody positivity, despite the presence of antibody in the injected material.