Following a publication on the sudden outbreak of hepatitis A (HAV) infections in Italian hemophiliacs after treatment with a solvent detergent (S/D) virus-inactivated factor VIII concentrate, we retrospectively examined our patients for HAV seroconversions and clinical symptoms of an acute HAV infection at our center. We found that between 1988 and 1992, 17 hemophilia A patients displayed HAV IgG seroconversions. Of these patients, 13 also had an HAV IgM seroconversion and 10 exhibited clinical symptoms of an acute HAV infection. A feature common to all was the fact that in the months prior to seroconversion they had been treated exclusively with the S/D-virus-inactivated product Octavi manufactured by Octapharma in Düsseldorf (FRG). None of the hemophilia A patients who had been treated with other products and who were susceptible to hepatitis A displayed seroconversion in the above-mentioned time span.