Many patients express concern about the risk of an infection from blood transfusion. Blood transfusion is one of the safest therapies available, but its risks should never be trivialized when talking with patients. The most common infectious complication is hepatitis C, which occurs in 2% to 4% of transfused patients. Hepatitis B occurs in fewer than 1% of such patients. The risk of HIV infection from a blood transfusion is less than 1 in 100,000 in the United States. Explanation of risks is most effective when comparisons are meaningful and phrased from the patient's point of view.