Hepatitis A virus (HAV) infection via the parenteral route is not common. To investigate this further, we obtained the fresh frozen plasma (FFP) component from a unit of whole blood provided by an HAV-infected donor and attempted to quantify and characterize the virus in this material. Despite repeated efforts at culture and cesium banding, HAV was not detected by these methods. However, a hepatitis-A-specific antibody capture assay did demonstrate an occasional HAV-like particle upon electron microscopic analysis of plasma-derived material. We conclude that the quantity of virus present in HAV-contaminated blood or products may be variable and therefore of insufficient numbers as to induce clinically apparent disease in all recipients.