Preparations of intramuscular immunoglobulins (IMIGs) have not been reported to transmit viral disease since the inclusion of third-generation tests screening donor blood for hepatitis B virus. IMIGs and intravenous immunoglobulins (IVIGs) have never been a source of transmission of human immunodeficiency viruses. One episode of hepatitis B transmission by IVIGs caused by the addition of contaminated material during the manufacturing process, has been reported. Between 1983 and 1994 there were at least 17 reports of transmission of non-A, non-B hepatitis or 'transaminitis' connected with the application of six IVIG preparations. These preparations were produced without including a validated virus-inactivation method in the manufacturing process. Careful analysis of these accidents demonstrates that minimization of virus contamination of source plasma, guarantee of good manufacturing practice, as well as application of an accepted virus-inactivation procedure are essential requirements for the production of safe immunoglobulin preparations.