Inactivation of Hepatitis B virus associated DNA polymerase was studied in factor IX concentrate (coagulation factors II, VII, IX and X) by heat pasteurization (60 degrees C, 10 hr) and by alkylating agents iodoacetic acid and iodoacetamide. DNA polymerase appeared to reach a residual level which occurred in human serum albumin at 60 degrees C, 10 hr under comparable spike level of hepatitis B virus. Of the four coagulation factors, factor IX activity was most susceptible to inactivation procedures with 40-50% recovery across heat pasteurization and approximately 70% recovery across iodoacetic acid treatment. Factor IX specific activities of the treated concentrates were greater than or equal to 70% of the untreated controls with no appreciable change of corresponding NAPTT values. Factor IX concentrates subjected to such inactivation procedures should reduce the potential for hepatitis B virus transmission.