It's easy to view an allograft as a surgical supply on the order of sutures, scalpels and sponges. You don't know where it came from and you don't bother asking. But allografts can be sources of infectious disease. More than 1.5 million allograft tissues are implanted into patients annually, with the number increasing every year, according to the American Association of Tissue Banks. The headlines over the past year about patients being implanted with tissue contaminated by mold, fungi, bacteria and viruses are good reminders that allografts can do more harm than good if they're not strictly controlled and delicately treated before we transplant them (see "Do You Know Where Your Allograft Tissue Is Coming From?" on page 68).