A total of 210 patients consecutively submitted to heart surgery at the Parma University Hospital and transfused with 1,898 units of blood were followed after transfusion in order to evaluate both the incidence of anti-hepatitis C virus (HCV) seroconversion in non-A, non-B post-transfusion hepatitis (PTH-NANB) cases and the usefulness of the screening for anti-HCV in comparison with that for serum glutamic pyruvic transaminase (SGPT) values in preventing PTH-NANB transmission. Fifteen recipients developed PTH-NANB (group A); ten of them (66.6%) showed anti-HCV seroconversion within 3-12 months. Eight of the ten anti-HCV positive patients developed chronic hepatitis, but none of the five PTH-NANB anti-HCV negative did. None of the 15 controls (group B) randomly chosen among the patient population showed anti-HCV seroconversion. A close correlation with the transmission of PTH was showed by anti-HCV positivity but not by SGPT elevation in blood donors. Eleven of 172 blood products transfused to group A but none of 139 products transfused to group B were anti-HCV positive. The incidence of elevated SGPT values was similar between the two groups of the transfused blood products. Nevertheless, the correlation observed between anti-HCV positivity and SGPT levels in the blood products involved in PTH confirms the need to exclude blood donors with abnormal SGPT values. On the whole, anti-HCV screening of donors showed a predictive value higher than that of SGPT (100% vs. 53.3%), allowing a minor blood donation exclusion.(ABSTRACT TRUNCATED AT 250 WORDS)