Consecutive patients undergoing open-heart surgery at Georgetown University and Fairfax Hospital will be admitted to the study if:

They are 18 years of age or older;

They provide informed consent;

They reside in the United States and will be available for at least six months of follow up.

Patients with known hepatitis C or hepatitis B virus carriers with or without evidence of chronic hepatitis will be excluded.

Persons with a history of prior hepatitis will not be excluded, but will be analyzed as a separate cohort.

Patients with close exposure (household or sexual contact) to hepatitis in the preceding six months will be excluded.

Patients with elevated pre-operative alanine aminotransferase (ALT) will be excluded. An aspartate aminotransferase (AST) of between 45 and 75 IU per L will not serve as cause for exclusion if the corresponding ALT is normal on at least two occasions.

A preoperative AST greater than 75 IU/L will serve to exclude patients from study independent of the ALT.

Patients with blood transfusion in the six months preceding surgery will be excluded. Patients will also be retrospectively excluded if they receive blood more than one month after surgery.

The six month followup period will be timed from the date of the last transfusion.

Patients with alcoholism or other known liver or active biliary tract disease at the time of entrance into the study will be excluded.

Patients with inadequate veins from which to obtain required samples will be excluded.