The present study was set up to evaluate the efficacy of hyperimmune anti-CMV immunoglobulins (IVIG) in the prophylaxis of CMV infection in five patients suffering from dilatative myocardiopathy and submitted to hearth transplant. Different commercial IVIG were tested for anti-CMV neutralizing antibodies before administrated them to patients; the lots immunochemically prepared by PEG resulted to have the highest anti-CMV titer. IVIG treatment, when administered at high doses and at closes intervals of time, proved able to prevent and control CMV infections; when treatment was stopped, a primary infection occurred, easily controlled by short courses of DHPG. Even if our survey was limited to only five cases, it should be emphasized that after the suspension of the therapy, clinical symptoms were restricted to simple mononucleosis syndrome without organ disease. Furthermore it should be noted that during IVIG therapy no immediate or delayed adverse effects were observed.