Several groups including ours at Hyland have studied the incidence of HTLV-III/LAV seroconversion and non-A, non-B hepatitis (NANBH) in recipients of products made from unscreened plasma. Of 18 previously untreated patients who received heat-treated factor VIII concentrate (HEMOFIL T), none seroconverted for HTLV-III/LAV. However, 11 of 13 similarly treated patients showed aminotransferase elevations indicative of NANBH. None of 21 patients receiving anti-inhibitor coagulant complex (Autoplex) seroconverted for HTLV-III/LAV, while 28 of 50 patients receiving other forms of treatment did seroconvert. Of 30 recipients of AUTOPLEX, 9 had elevated aminotransferase levels. Since all patients had hepatitis B markers when the study began, a diagnosis of NANBH cannot be made. Of 16 patients who received large doses of immune globulin for intravenous administration (IGIV, GAMMAGARD), none seroconverted for HTLV-III/LAV. Retrospective and prospective studies of 157 recipients of GAMMAGARD did not reveal a single case of NANBH attributable to receipt of this product. In contrast, NANBH has occurred following administration of HEMOFIL T, indicating that heating in the dried state does not eliminate the NANBH agent(s). In spite of lingering concerns about NANBH infectivity, the available data strongly suggest that heat treatment and/or cold ethanol fractionation render these plasma products safe from HTLV-III infectivity.