To evaluate the safety and efficacy of passive immunotherapy for advanced human immunodeficiency virus (HIV) infection, a randomized, double-blind, controlled trial of human anti-HIV hyperimmune plasma was conducted. Sixty-three subjects with stage IV HIV disease (AIDS) were randomized to received 250 mL of either HIV-immune plasma or HIV antibody-negative plasma every 4 weeks. Although nonsignificant trends toward improved survival and delayed occurrence of a new opportunistic infection were noted, no significant effects on absolute CD4 lymphocyte counts or quantitative HIV viremia were seen. The only notable toxicity was the allergenicity to be expected from infusing plasma products, usually manifesting as urticaria. Thus, results do not rule out the potential usefulness of passive immunization with different preparations, but did fail to demonstrate clinical benefit of the product studied.