We carried out an analysis of the randomized clinical trials published on the effectiveness of hyperimmune immunoglobulins for prevention of cytomegalovirus (CMV) infection or disease in CMV-seronegative recipients of allogeneic bone marrow transplantation (BMT). The clinical trials were identified by searching a number of computerized literature databases, by reviewing bibliographies of the paper examined and by consulting experts. All studies we selected were randomized and were aimed at evaluating the efficacy of hyperimmune immunoglobulins in comparison with a control group receiving no immunoglobulins. The results of this analysis indicate that hyperimmune immunoglobulins reduce the frequency of CMV infection (overall odds ratio = 0.444; 95% confidence interval 0.237-0.832, p = 0.011) and CMV related disease (overall odds ratio = 0.445; 95% confidence interval 0.223-0.887, p = 0.021) in CMV-seronegative recipients of allogeneic BMT.