The clinical plastic surgeon needs to be able to determine which of his or her patients are low risk and which of his or her patients require additional tests. Which patients can be operated on today, and which patients need to be delayed and possibly treated preoperatively? After a review of the literature, we present these guidelines: 1. Take a good history. 2. Stratify the risk to the patient. 3. Test as indicated. a. Don't necessarily rely on the bleeding time. b. Be aware of the high false-positive rate of coagulation tests. 4. Be mindful of the effects of certain medicines. 5. "Surgical" bleeding is the most common cause of bleeding and should prompt reoperation if coagulation tests are negative. 6. Consult a hematologist early as questions arise, particularly in patients stratified to moderate- and high-risk groups.