To the Editor: In the late 1960s, hemophilia treatment was dramatically altered with the discovery of cryoprecipitate. By the mid-1970s, clotting-factor concentrates became readily available, providing additional treatment options. However, product safety has been and continues to be a major problem. Hepatitis B, non-A, non-B hepatitis, and the acquired immunodeficiency syndrome are transmitted by these blood derivatives. The majority of patients are positive for human immunodeficiency virus (HIV), and at least 75 percent of patients with hemophilia have sequelae of non-A, non-B hepatitis. High-purity monoclonally derived products are now available that are virtually free of extraneous plasma proteins. It appears ….