AIMS: To investigate the impact of hepatitis C virus (HCV) infection in long term survivors of haematological malignancy treated before the introduction of blood donor screening in September 1991. METHOD: Patients were tested for evidence of HCV infection by third generation enzyme linked immunosorbent assays, a recombinant immunoblot assay and reverse transcriptase polymerase chain reaction. Serum aspartate aminotransferase activities were measured. The number and type of blood component units received by each patient were recorded. RESULTS: Forty two patients were studied who had received a total of 7143 blood component units. Two patients (4.8%) were found to have HCV infection, both had histological evidence of chronic active hepatitis, and one is now receiving treatment with alpha-interferon. Both of these patients had been missed by the ongoing look-back programme which aims to detect recipients of all known HCV infected blood components. CONCLUSION: Although HCV infection affects a minority of long term survivors of haematological malignancy, infected patients may benefit from alpha-interferon treatment. The screening of all patients treated for haematological malignancy before September 1991 is advocated.